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Overview of Headache
May 11, 2012
A headache is pain in any part of the head, including the scalp, upper neck, face, and interior of the head. Headaches are one of the most common reasons people visit a doctor. Headaches interfere with the ability to work and do daily tasks. Some peo...
Tension-Type Headaches
May 11, 2012
A tension-type headache is usually mild to moderate pain that feels like a band tightening around the head.
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Migraines
May 11, 2012
A migraine headache is typically a pulsating or throbbing pain that ranges from moderate to severe. It can affect one or both sides of the head. It is worsened by physical activity, light, sounds, or odors and is accompanied by nausea, vomit...
Cluster Headaches
May 11, 2012
A cluster headache causes severe pain that is felt at the temple or around the eye on one side of the head and that lasts a relatively short time (usually 30 minutes to 1 hour). Headaches usually occur regularly during a 1- to 3-month period...
Idiopathic Intracranial Hypertension
May 11, 2012
Idiopathic intracranial hypertension (benign intracranial hypertension, pseudotumor cerebri) is characterized by increased pressure within the skull (intracranial pressure), without any evidence of a cause.
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Low-Pressure Headache
May 11, 2012
Low-pressure headaches result when cerebrospinal fluid is removed during a spinal tap (lumbar puncture) or leaks out because of a cyst or tear in one of the layers of tissues that cover the spinal cord (meninges). Loss of this fluid, which f...
Overview of the Anus and Rectum
May 11, 2012
The anus is the opening at the end of the digestive tract where stool leaves the body. The rectum is the section of the digestive tract above the anus where stool is held before it passes out of the body through the anus....
Anal Fissure
May 11, 2012
An anal fissure is a tear or ulcer in the lining of the anus.
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Anal Itching
May 11, 2012
Itching of the anus and the skin around the anus (perianal skin) is called anal itching or pruritus ani. ...
Anorectal Abscess
May 11, 2012
An anorectal abscess is a pus-filled cavity caused by bacteria invading a mucus-secreting gland in the anus and rectum.
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Anorectal Fistula
May 11, 2012
An anorectal fistula is an abnormal channel that leads from the anus or rectum usually to the skin near the anus but occasionally to another organ, such as the vagina.
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Foreign Objects in the Rectum
May 11, 2012
Swallowed objects, such as toothpicks, chicken bones, or fish bones, may become lodged at the junction between the anus and rectum (anorectal junction). Also, enema tips, surgical sponges or instruments, thermometers, and objects used for sexual stim...
Hemorrhoids
May 11, 2012
Hemorrhoids are dilated, twisted (varicose) veins located in the wall of the rectum and anus.
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Levator Syndrome
May 11, 2012
Levator syndrome is sporadic pain in the rectum caused by spasm of a muscle near the anus (the levator ani muscle).
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Pilonidal Disease
May 11, 2012
Pilonidal disease is an infection caused by a hair that injures the skin at the top of the cleft between the buttocks.
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Proctitis
May 11, 2012
Proctitis is inflammation of the lining of the rectum (rectal mucosa).
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Rectal Prolapse
May 11, 2012
Rectal prolapse is a painless protrusion of the rectum through the anus.
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Overview of the Thyroid Gland
May 11, 2012
The thyroid is a small gland, measuring about 2 inches (5 centimeters) across, that lies just under the skin below the Adam's apple in the neck. The two halves (lobes) of the gland are connected in the middle (called the isthmus), giving the thyroid ...
Hyperthyroidism
May 11, 2012
Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions.
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Hypothyroidism
May 11, 2012
Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions.
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Hashimoto's Thyroiditis
May 11, 2012
Hashimoto's thyroiditis is chronic, autoimmune inflammation of the thyroid.
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Subacute Thyroiditis
May 11, 2012
Subacute thyroiditis is acute inflammation of the thyroid, probably caused by a virus.
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Silent Lymphocytic Thyroiditis
May 11, 2012
Silent lymphocytic thyroiditis is painless, autoimmune inflammation of the thyroid that typically develops after childbirth and goes away on its own.
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Goiter
May 11, 2012
Goiter is noncancerous enlargement of the thyroid gland.
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Thyroid Cancer
May 11, 2012
The cause of thyroid cancer is not known, but the thyroid gland is very sensitive to radiation, which may cause cancerous changes. Thyroid cancer is more common among people who were treated with radiation to the head, neck, or chest, most often for ...
Introduction
May 11, 2012
Gynecologic disorders are disorders that affect the female reproductive system. The most common symptoms of gynecologic disorders include pelvic pain, vaginal itching, vaginal discharge, abnormal vaginal bleeding, and breast pain and lumps (). The si...
Pelvic Pain
May 11, 2012
Pelvic pain is discomfort that occurs in the lowest part of the torso, the area below the abdomen and between the hipbones. It does not include pain that occurs externally in the genital area (vulva). Many women have pelvic pain. Pain is considered c...
Vaginal Bleeding
May 11, 2012
Abnormal vaginal bleeding includes any vaginal bleeding that occurs...
Vaginal Discharge
May 11, 2012
A discharge from the vagina may occur normally or may result from inflammation of the vagina (vaginitis), which may be due to an infection. The genital area (vulva)—the area around the opening of the vagina—may also be inflamed. Depending on the caus...
Vaginal Itching
May 11, 2012
Vaginal itching may involve the vagina or the genital area (vulva), which contains the external genital organs. Itching is an unpleasant sensation that seems to require scratching for relief....
Introduction
May 11, 2012
Symptoms that occur during pregnancy may be normal () or may indicate a problem. A problem may be related to the pregnancy or to another disorder, and evaluation by a doctor may be required. Some symptoms should always be reported immediately to a do...
Nausea and Vomiting During Early Pregnancy
May 11, 2012
Up to 80% of pregnant women have nausea and vomiting to some extent. Nausea and vomiting are most common and most severe during the 1st trimester. Although commonly called morning sickness, such symptoms may occur at any time during the day....
Pelvic Pain During Early Pregnancy
May 11, 2012
Early in pregnancy, many women have pelvic pain. Pelvic pain refers to pain in the lowest part of the torso, in the area below the abdomen and between the hipbones (pelvis). The pain may be sharp or crampy (like menstrual cramps) and may come and go....
Swelling During Late Pregnancy
May 11, 2012
As pregnancy progresses, fluid may accumulate in tissues, usually in the feet, ankles, and legs, causing them to swell and appear puffy. This condition is called edema. Occasionally, the face and hands also swell. Some fluid accumulation during pregn...
Vaginal Bleeding During Early Pregnancy
May 11, 2012
During the first 20 weeks of pregnancy, 20 to 30% of women have vaginal bleeding. In about half of these women, the pregnancy ends in a miscarriage. If miscarriage does not occur immediately, problems later in the pregnancy are more likely. For examp...
Vaginal Bleeding During Late Pregnancy
May 11, 2012
During late pregnancy (after 20 weeks), 3 to 4% of women have vaginal bleeding. Such women are at risk of losing the baby or of bleeding excessively (hemorrhaging). Sometimes so much blood is lost that blood pressure becomes dangerously low (causing ...
One-Page
Mar 1, 2011
People think healthy living involves rare treasures and dark secrets—the exotic plant from a Tibetan meadow, the secret advice from a sage in a remote village—or years of intense study and practice. Actually, the truth is hidden in plain sight, and i...
Blood Vessels and Lymph Nodes
Mar 1, 2010
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Brain and Spinal Cord
Mar 1, 2010
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Digestive System
Mar 1, 2010
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Epithelium: Surfaces of the Body
Mar 1, 2010
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Head and Neck
Mar 1, 2010
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Heart-Lung Connections
Mar 1, 2010
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Muscle-Bone Connections
Mar 1, 2010
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Urinary System
Mar 1, 2010
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Mar 1, 2010
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Mar 1, 2010
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Updates
Mar 1, 2010
The online version of The Merck Manual—Second Home Edition takes advantage of the flexibility of the web to present updates, changes, and corrections on a regular basis. Thus, the online version may contain material not yet in print. Details on updat...
Selected Links
Mar 1, 2010
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Weights and Measures
Mar 1, 2010
In medicine, precise measurements are necessary—for example, when various substances are measured in laboratory tests to evaluate health or make a diagnosis. Different units of measure may be used depending on the substance. Usually, the metric syste...
Common Medical Tests
Mar 1, 2010
A large number of tests are widely available. Many tests are specialized for a particular disorder or group of related disorders (which are usually described with the appropriate disorders in this book). Other tests are commonly used for a wide range...
Drug Names: Generic and Trade
Mar 1, 2010
Most prescription drugs placed on the market are given trade names (also called proprietary, brand, or specialty names) to distinguish them as being produced and marketed exclusively by a particular manufacturer. In the United States, these names are...
Introduction
Mar 1, 2010
This collection of resources is selective and restricted largely to national organizations in the United States, many of which have local chapters. Sites chosen are generally not-for-profit and usually offer information or support rather than advocac...
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Committed to Providing Medical Information: Merck and The Merck Manuals
Mar 1, 2010
In 1899, the American drug manufacturer Merck & Co. first published a small book titled Merck's Manual of the Materia Medica. It was meant as an aid to physicians and pharmacists, reminding doctors that “Memory is treacherous.” Compact in size, easy ...
Preface
Mar 1, 2010
People are now taking increasing responsibility for their own health care. Many come to their doctor's office with printouts from the Internet of the latest scientific studies. People now evaluate options—such as whether to have surgery, radiation th...
Editorial Board
Mar 1, 2010
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Editors
Mar 1, 2010
EDITOR-IN-CHIEF
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Publishing and Production Staff
Mar 1, 2010
MERCK PUBLISHING GROUP
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Consultants
Mar 1, 2010
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Contributors
Mar 1, 2010
We gratefully acknowledge the expertise of the contributors to our current online version. The subject(s) that they are responsible for are listed after their affiliations....
Reviewers for Selected Chapters
Mar 1, 2010
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Special Note to Readers
Mar 1, 2010
The contributors, reviewers, editors, and publisher have made extensive efforts to ensure that the information is accurate and conforms to the standards accepted at the time of publication. However, constant changes in information resulting from cont...
A Guide for Readers
Mar 1, 2010
The Merck Manual Home Health Handbook, Online Version is organized into sections, chapters, and topics, all of which are listed alphabetically. The names of some chapters and topics have been edited (and may be different from those in the print ...
Understanding Medical Terms
Mar 1, 2010
At first glance, medical terminology can seem like a foreign language. But often the key to understanding medical terms is focusing on their components (prefixes, roots, and suffixes). For example, spondylolysis is a combination of "spondylo, " which...
Overview of Viral Infections
Nov 1, 2009
A virus is a small infectious organism—much smaller than a fungus or bacterium—that must invade a living cell to reproduce (replicate). The virus attaches to a cell (called the host cell), enters it, and releases its DNA or RNA inside the ce...
Smallpox
Nov 1, 2009
Smallpox (variola) is a highly contagious, very deadly disease caused by the smallpox virus.
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Common Cold
Nov 1, 2009
The common cold is a viral infection of the lining of the nose, sinuses, throat, and large airways.
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Influenza
Nov 1, 2009
Influenza (flu) is infection of the lungs and airways with one of the influenza viruses. It causes a fever, runny nose, sore throat, cough, headache, muscle aches (myalgias), and a general feeling of illness (malaise).
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Herpes Simplex Virus Infections
Nov 1, 2009
Herpes simplex virus infection causes recurring episodes of small, painful, fluid-filled blisters on the skin, mouth, lips (cold sores), eyes, or genitals.
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Shingles
Nov 1, 2009
Shingles (herpes zoster) is infection that results from reactivation of the varicella-zoster virus, the virus that causes chickenpox.
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Epstein-Barr Virus (EBV) Infection
Nov 1, 2009
Epstein-Barr virus causes a number of diseases, including infectious mononucleosis.
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Cytomegalovirus (CMV) Infection
Nov 1, 2009
Cytomegalovirus infection is a common herpesvirus infection with a wide range of symptoms: from no symptoms to fever and fatigue (resembling infectious mononucleosis) to severe symptoms involving the eyes, brain, or other internal organs.
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Hemorrhagic Fevers
Nov 1, 2009
Hemorrhagic fevers are serious viral infections characterized by bleeding.
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Hantavirus Infection
Nov 1, 2009
Hantavirus infection is a viral disease that is spread from rodents to people. The virus can cause severe infections of the lungs (with cough and shortness of breath) or kidneys (with rash, abdominal pain, and sometimes kidney failure).
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Yellow Fever
Nov 1, 2009
Yellow fever is a mosquito-borne viral disease that occurs mainly in the tropics.
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Dengue Fever
Nov 1, 2009
Dengue fever is a mosquito-borne viral infection that causes fever, generalized body aches, and, if severe, external and internal bleeding.
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Severe Acute Respiratory Syndrome (SARS)
Nov 1, 2009
Severe acute respiratory syndrome is a viral infection that causes flu-like symptoms.
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Burns
Apr 29, 2009
Burns are injuries to tissue that result from heat, electricity, radiation, or chemicals.
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Overview of Problems in Newborns
Feb 1, 2009
Although most infants are delivered at full term and have no problems, some infants may have medical problems related to factors that occur before birth, such as any health problems or habits of the mother. Examples of health problems are diabetes, h...
Birth Injury
Feb 1, 2009
Birth injury is damage sustained during the birthing process, usually occurring during transit through the birth canal.
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Prematurity
Feb 1, 2009
A premature newborn is delivered before 37 weeks of development in the uterus. A premature newborn has underdeveloped organs, which may not be ready to function outside of the uterus.
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Postmaturity
Feb 1, 2009
A postmature newborn is delivered after more than 42 weeks in the uterus.
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Small for Gestational Age (SGA)
Feb 1, 2009
A newborn, whether delivered preterm, term, or postterm, whose weight is less than that of 90% of newborns of the same gestational age at birth (below the 10th percentile) is considered small for gestational age.
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Large for Gestational Age (LGA)
Feb 1, 2009
A newborn, whether delivered preterm, term, or postterm, whose weight is above that of 90% of newborns of the same gestational age at birth (above the 90th percentile) is considered large for gestational age.
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Respiratory Distress Syndrome
Feb 1, 2009
Respiratory distress syndrome (hyaline membrane disease) is a breathing disorder of premature newborns in which the air sacs (alveoli) in a newborn's lungs do not remain open because the production of a substance that coats the alveoli (surf...
Transient Tachypnea
Feb 1, 2009
Transient tachypnea of the newborn (rapid breathing of the newborn, neonatal wet lung syndrome) is temporary difficulty with breathing and low blood oxygen levels due to excessive fluid in the lungs after birth.
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Meconium Aspiration Syndrome
Feb 1, 2009
Meconium aspiration syndrome is respiratory distress in a newborn who has breathed (aspirated) meconium into the lungs before or around the time of birth.
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Persistent Pulmonary Hypertension
Feb 1, 2009
Persistent pulmonary hypertension is a serious disorder in which the arteries to the lungs remain narrowed (constricted) after delivery, thus limiting the amount of blood flow to the lungs and therefore the amount of oxygen in the bloodstrea...
Pneumothorax in Newborns
Feb 1, 2009
Pneumothorax is a collection of air between the lung and the chest wall that develops when air leaks out of the lung.
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Bronchopulmonary Dysplasia
Feb 1, 2009
Bronchopulmonary dysplasia is a chronic lung disorder caused by repetitive lung injury.
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Apnea of Prematurity
Feb 1, 2009
Apnea of prematurity is a pause in breathing that lasts for more than 20 seconds.
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Retinopathy of Prematurity (ROP)
Feb 1, 2009
Retinopathy of prematurity is a disorder in which the small blood vessels in the back of the eye (retina) grow abnormally.
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Necrotizing Enterocolitis (NEC)
Feb 1, 2009
Necrotizing enterocolitis is injury to the inner surface of the intestine. This disorder occurs most often in very premature newborns.
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Hyperbilirubinemia
Feb 1, 2009
Hyperbilirubinemia is an abnormally high level of bilirubin (a pigment produced from the breakdown of red blood cells) in the blood.
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Anemia in the Newborn
Feb 1, 2009
Anemia is a disorder in which there are too few red blood cells in the blood.
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Polycythemia in the Newborn
Feb 1, 2009
Polycythemia is an abnormally high concentration of red blood cells.
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Thyroid Disorders in the Newborn
Feb 1, 2009
Thyroid disorders occur if the thyroid gland produces too little thyroid hormone (hypothyroidism) or too much thyroid hormone (hyperthyroidism)....
Sepsis in the Newborn
Feb 1, 2009
Sepsis is bacterial infection in the blood.
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Fussiness, Excessive Crying, and Colic
Feb 1, 2009
Fussiness is the inability of an infant to settle down or be soothed. Excessive crying is hours-long periods of crying by a healthy infant whose basic needs are met. Colic is a pattern of weeks-long, excessive periods of crying th...
Teething
Feb 1, 2009
A child's first tooth usually appears by 6 months of age, and a complete set of 20 primary or first teeth usually develops by age 3. Before a tooth appears, the child may cry, be irritable, and sleep and eat poorly. The child may drool, have red and ...
Feeding Problems in Infants and Young Children
Feb 1, 2009
Feeding problems in infants and young children are usually minor but sometimes have serious consequences....
Bowel Problems in Infants and Young Children
Feb 1, 2009
The number and consistency of stools for a healthy child vary with age and diet. For example, infants who are breastfed normally have mustard-colored stools that are soft and seedy. However, repeated watery bowel movements for a time lasting longer t...
Separation Anxiety
Feb 1, 2009
Separation anxiety is the fear young children have that their parents will leave them.
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Rashes in Infants
Feb 1, 2009
Skin rashes in infants and young children are not usually serious and can have various causes....
Undescended and Retractile Testes
Feb 1, 2009
Undescended testes (cryptorchidism) are testes that remain in the abdomen instead of descending into the scrotum just before birth.
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Fever in Infants and Young Children
Feb 1, 2009
Fever is a rise in body temperature in response to infection, injury, or inflammation (see ).
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Failure to Thrive
Feb 1, 2009
Failure to thrive is a delay in physical growth and weight gain that can lead to delays in development and maturation.
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Apparent Life-Threatening Event (ALTE)
Feb 1, 2009
An apparent life-threatening event (ALTE) is the sudden occurrence of certain alarming symptoms such as prolonged periods of no breathing (apnea), change in color or muscle tone, coughing, and gagging in children under 1 year of age.
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Sudden Infant Death Syndrome (SIDS)
Feb 1, 2009
Sudden infant death syndrome (SIDS) is the sudden, unexpected death of a seemingly healthy infant during sleep, in whom a thorough postmortem examination does not show a cause.
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Overview of Behavioral Problems in Young Children
Feb 1, 2009
Children acquire many skills as they grow. Some skills, such as controlling urine and stool, depend mainly on the level of maturity of the child's nerves and brain. Others, such as behaving appropriately at home and in school, are the result of a com...
Eating Problems in Young Children
Feb 1, 2009
Some eating problems are behavioral in nature. Parents of young children often are concerned that their children are not eating enough or eating too much, eating the wrong foods, refusing to eat certain foods, or engaging in inappropriate mealtime be...
Bed-Wetting
Feb 1, 2009
About 30% of children still wet the bed at age 4, 10% at age 6, 3% at age 12, and 1% at age 18. Bed-wetting is more common among boys and seems to run in families....
Encopresis
Feb 1, 2009
Encopresis is the accidental passing of bowel movements that is not caused by illness or physical abnormality.
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Sleep Problems in Children
Feb 1, 2009
Most children sleep for a stretch of at least 5 hours by age 3 months but then experience periods of night waking later in the first years of life, often associated with illness. As they get older, the amount of rapid eye movement (REM) sleep increas...
Temper Tantrums
Feb 1, 2009
Temper tantrums are common in childhood. They usually appear toward the end of the first year, are most common between ages 2 and 4, and are typically infrequent after age 5. If tantrums are frequent after age 5, they may persist throughout childhood...
Breath-Holding Spells
Feb 1, 2009
A breath-holding spell is an episode in which the child stops breathing and loses consciousness for a short period immediately after a frightening or emotionally upsetting event or a painful experience.
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School Avoidance
Feb 1, 2009
School avoidance occurs in about 5% of all school-aged children and affects girls and boys equally. It usually occurs between ages 5 and 6 and between ages 10 and 11....
Introduction
Feb 1, 2009
During adolescence (usually encompassing ages 10 to the late teens or early 20s), children become young adults. They mature socially and physically. Notably, they become sexually mature and socially independent. During this time, the adolescent devel...
Physical and Sexual Development
Feb 1, 2009
Normal growth during adolescence includes both an increase in body size and sexual maturation (puberty). The timing and speed with which these changes occur vary and are affected by both heredity and environment. During adolescence, boys and girls re...
Intellectual and Behavioral Development
Feb 1, 2009
In early adolescence, a child begins to develop the capacity for abstract, logical thought. This increased sophistication leads to an enhanced awareness of self and the ability to reflect on one's own being. Because of the many noticeable physical ch...
Emotional Development
Feb 1, 2009
During adolescence, the regions of the brain that control emotions develop and mature. This phase is characterized by seemingly spontaneous outbursts that can be challenging for parents and teachers who often receive the brunt. Adolescents gradually ...
Social and Psychologic Development
Feb 1, 2009
The family is the center of social life for children. During adolescence, the peer group begins to replace the family as the child's primary social focus. Peer groups are often established because of distinctions in dress, appearance, attitudes, hobb...
Development of Sexuality
Feb 1, 2009
The onset of sexual maturation (puberty) typically is accompanied by an interest in sexual anatomy, which may be a source of anxiety. As adolescents mature emotionally and sexually, they may begin to engage in sexual behaviors. Masturbation is common...
Preventive Health Care Visits
Feb 1, 2009
Annual health care visits allow doctors and other health care practitioners to monitor physical growth and sexual maturation and provide advice and counseling. Height, weight, and blood pressure should be monitored at every yearly health care visit. ...
Asthma in Children
Feb 1, 2009
Asthma is a recurring inflammatory lung disorder in which certain stimuli (triggers) inflame the airways and cause them to temporarily narrow, resulting in difficulty breathing.
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Bronchiolitis
Feb 1, 2009
Bronchiolitis is an infection that affects the lower respiratory tract of infants and young children under 24 months of age.
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Croup
Feb 1, 2009
Croup (laryngotracheobronchitis) is an inflammation of the windpipe (trachea) and voice box (larynx) typically caused by a contagious viral infection that causes cough, a loud squeaking noise (stridor), and sometimes difficulty with breathin...
Bacterial Tracheitis
Feb 1, 2009
Bacterial tracheitis (pseudomembranous croup) is an infection of the windpipe (trachea) caused by bacteria.
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Seizures in Children
Feb 1, 2009
Seizures are a periodic disturbance of the brain's electrical activity, resulting in some degree of temporary brain dysfunction.
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Neurofibromatosis
Feb 1, 2009
Neurofibromatosis is a genetic disorder in which many soft, fleshy growths of nerve tissue (neurofibromas) grow under the skin and in other parts of the body.
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Sturge-Weber Syndrome
Feb 1, 2009
Sturge-Weber syndrome is a rare disorder affecting small blood vessels. It is characterized by a port-wine birthmark on the face, a blood vessel tumor (angioma) in the tissues that cover the brain, or both.
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Tuberous Sclerosis
Feb 1, 2009
Tuberous sclerosis is a hereditary disorder that causes abnormalities in the brain, changes in the skin and sometimes tumors to develop in vital organs, such as the heart and lungs.
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Von Hippel–Lindau Disease
Feb 1, 2009
Von Hippel-Lindau disease is a rare hereditary disorder that causes tumors to develop in several organs.
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Overview of Hereditary Metabolic Disorders
Feb 1, 2009
Most of the foods and drinks people ingest are complex materials that the body must break down into simpler substances. This process may involve several steps. The simpler substances are then used as building blocks, which are assembled into...
Disorders of Carbohydrate Metabolism
Feb 1, 2009
Carbohydrates are sugars. Some sugars are simple, and others are more complex. Sucrose (table sugar) is made of two simpler sugars called glucose and fructose. Lactose (milk sugar) is made of glucose and galactose. Both sucrose and lactose must be br...
Disorders of Amino Acid Metabolism
Feb 1, 2009
Amino acids are the building blocks of proteins and have many functions in the body. Hereditary disorders of amino acid processing can result from defects either in the breakdown of amino acids or in the body's ability to get amino acids into cells. ...
Disorders of Lipid Metabolism
Feb 1, 2009
Fats (lipids) are an important source of energy for the body. The body's store of fat is constantly broken down and reassembled to balance the body's energy needs with the food available. Groups of specific enzymes help the body break down and proces...
Definition of Developmental Disorders
Feb 1, 2009
Developmental disorders, including attention-deficit/hyperactivity disorder, autism spectrum disorders, learning disabilities, and intellectual disability, are neurologically based conditions that can interfere with the acquisition, retention, or app...
Attention-Deficit/Hyperactivity Disorder
Feb 1, 2009
Attention-deficit/hyperactivity disorder (ADHD) is poor or short attention span and impulsiveness inappropriate for the child's age. Some children are also hyperactive.
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Autism Spectrum Disorders
Feb 1, 2009
Autism spectrum disorders are disorders in which young children cannot develop normal social relationships, use language abnormally or not at all, behave in compulsive and ritualistic ways, and may fail to develop normal intelligence.
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Learning Disorders
Feb 1, 2009
Learning disorders involve an inability to acquire, retain, or broadly use specific skills or information, resulting from deficiencies in attention, memory, or reasoning and affecting academic performance.
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Intellectual Disability
Feb 1, 2009
Mental retardation/intellectual disability is significantly subaverage intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily living.
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Overview of Mental Health Disorders in Children
Feb 1, 2009
Several important mental health disorders, such as depression and eating disorders (see ), often develop during childhood and adolescence. Some disorders, such as autism, develop only during childhood....
Childhood Schizophrenia
Feb 1, 2009
Childhood schizophrenia is a chronic disorder involving abnormal thought, perception, and social behavior.
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Depression in Children
Feb 1, 2009
Depression is a feeling of sadness or irritability intense enough to interfere with functioning. It may follow a recent loss or other sad event but is out of proportion to that event and persists beyond an appropriate length of time (see ).
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Bipolar Disorder in Children(Manic-Depressive Illness)
Feb 1, 2009
In bipolar disorder (sometimes called manic-depressive illness), periods of intense elation and excitation (mania) alternate with periods of depression and despair. Mood may be normal in between these periods.
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Suicidal Behavior in Children and Adolescents
Feb 1, 2009
Suicidal behavior is an action intended to harm oneself and includes suicide gestures, suicide attempts, and completed suicide.
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Conduct Disorder
Feb 1, 2009
A conduct disorder involves a repetitive pattern of behavior that violates the basic rights of others.
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Oppositional Defiant Disorder
Feb 1, 2009
Oppositional defiant disorder is a recurring pattern of negative, defiant, and disobedient behavior, often directed at authority figures.
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Anxiety Disorders in Children
Feb 1, 2009
Anxiety disorders are characterized by fear, worry, or dread that greatly impairs the ability to function and is out of proportion to the circumstances.
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Tic Disorders
Feb 1, 2009
Tics are rapid, repeated involuntary movements that are fundamentally purposeless.
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Somatoform Disorders in Children
Feb 1, 2009
In somatoform disorders, an underlying psychologic problem causes distressing or disabling physical symptoms.
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Overview of Sports Injuries
Feb 1, 2009
Sports injuries are common among athletes and other people who participate in sports. Certain injuries that are traditionally considered sports injuries can also occur in people who do not participate in sports. For example, homemakers and factory wo...
Shoulder Injuries
Feb 1, 2009
Rotator cuff injuries and labral tears are the most common shoulder injuries....
Elbow Injuries
Feb 1, 2009
Injuries can occur to the tendons that attach to the elbow....
Knee Injuries
Feb 1, 2009
Knee sprains, meniscal injuries, and runner's knee are common knee injuries....
Hamstring Injury
Feb 1, 2009
The muscles in the back of the thigh (hamstrings) can be strained (hamstring pull) in any running activity.
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Lower Leg Injuries
Feb 1, 2009
Shin splints, ankle sprains, Achilles tendinitis, rupture of the Achilles tendon, and stress fractures of the foot are common injuries to the lower leg....
Overview of Heat Disorders
Feb 1, 2009
Humans, who are warm-blooded animals, maintain their body temperature within 1 or 2 degrees of 98.6° F (37° C) as measured by mouth and 100.4° F (38° C) as measured rectally, despite large fluctuations in external temperatures. This internal...
Heat Cramps
Feb 1, 2009
Heat cramps are severe muscle spasms resulting from a combination of prolonged exercise, heavy sweating, and excessive water replacement in extreme heat.
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Heat Exhaustion
Feb 1, 2009
Heat exhaustion is excessive loss of salts (electrolytes) and fluids due to heat, leading to decreased blood volume that causes many symptoms, sometimes including fainting or collapse.
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Heatstroke
Feb 1, 2009
Heatstroke is a life-threatening condition that results in very high body temperature and malfunction of many organ systems.
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Radiation Injury
Feb 1, 2009
Radiation injury is damage to tissues caused by exposure to ionizing radiation.
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Overview of Diving Injuries
Feb 1, 2009
People who engage in deep-sea or scuba diving are at risk of a number of injuries. Diving in cold water can rapidly lead to hypothermia (dangerously low body temperature), which causes clumsiness and poor judgment. Cold water can also rarely trigger ...
Barotrauma
Feb 1, 2009
Barotrauma is tissue injury caused by a change in pressure, which compresses or expands gas contained in various body structures.
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Air Embolism
Feb 1, 2009
Air embolism is blockage of blood supply to organs caused by bubbles in an artery.
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Decompression Sickness
Feb 1, 2009
Decompression sickness (decompression illness, caisson disease, the bends) is a disorder in which nitrogen dissolved in the blood and tissues by high pressure forms bubbles as pressure decreases.
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Immersion Pulmonary Edema
Feb 1, 2009
Immersion pulmonary edema is sudden development of fluid in the lungs that typically occurs early during a dive and at depth.
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Gas Toxicity During Diving
Feb 1, 2009
Problems during diving can result from toxic effects of gases such as nitrogen, oxygen, carbon dioxide, and carbon monoxide.
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Recompression Therapy
Feb 1, 2009
Recompression therapy (hyperbaric oxygen therapy) involves giving 100% oxygen for several hours in a sealed chamber at pressures higher than 1 atmosphere.
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Diving Precautions and Prevention of Diving Injuries
Feb 1, 2009
Diving is a relatively safe recreational activity for healthy people who have been appropriately trained and educated. Diving safety courses offered by national diving organizations are widely available....
Altitude Illness
Feb 1, 2009
Altitude illness occurs because of a lack of oxygen at high altitudes.
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Introduction
Feb 1, 2009
Many creatures, including humans, bite when frightened or provoked. Bites may cause injuries ranging from superficial scratches to extensive wounds and often become infected with bacteria from the mouth of the biting creature....
Animal Bites
Feb 1, 2009
Although any animal may bite, dogs and, to a lesser extent, cats account for most bites in the United States. Owing to their popularity as household pets, dogs account for the majority of bites as a result of protecting their owners and territory. Ab...
Human Bites
Feb 1, 2009
Because human teeth are not particularly sharp, most human bites cause a bruise and only a shallow tear (laceration), if any. Exceptions are on fleshy appendages, such as the ears, nose, and penis, which may be severed. The clenched-fist injury, or f...
Snake Bites
Feb 1, 2009
Bites from nonpoisonous snakes rarely produce any serious problems. About 25 species of venomous (poisonous) snakes are native to the United States. The venomous snakes include pit vipers (rattlesnakes, copperheads, and cottonmouths) and coral snakes...
Lizard Bites
Feb 1, 2009
The only two lizards known to be poisonous are the beaded lizard of Mexico and the Gila monster, present in Arizona; Sonora, Mexico; and adjacent areas. The venom of these lizards is somewhat similar in content and effect to that of some pit vipers, ...
Spider Bites
Feb 1, 2009
Almost all spiders are poisonous. However, the fangs of most species are too short or too fragile to penetrate human skin. Although at least 60 species in the United States have been implicated in biting people, serious injury occurs mainly from only...
Bee, Wasp, Hornet, and Ant Stings
Feb 1, 2009
Stings by bees, wasps, and hornets are common throughout the United States. Some ants also sting. The average person can safely tolerate 10 stings for each pound of body weight. This means that the average adult could withstand more than 1,000 stings...
Puss Moth Caterpillar Stings
Feb 1, 2009
The venomous puss moth caterpillar (also called the asp) is present in the southern United States. It is teardrop shaped and has long silky hair, making it resemble a tuft of cotton or fur. When a puss moth caterpillar rubs or is pressed against a pe...
Insect Bites
Feb 1, 2009
Among the more common biting and sometimes bloodsucking insects in the United States are the following:...
Tick and Mite Bites
Feb 1, 2009
Ticks carry many diseases. For example, deer ticks may carry the bacteria that cause Lyme disease (see ). Other types of ticks may carry the bacteria that cause rickettsial or ehrlichial infections (see ). The bites of pajaroello ticks, which are pre...
Centipede and Millipede Bites
Feb 1, 2009
Some of the larger centipedes can inflict a painful bite, causing swelling and redness. Symptoms rarely persist for more than 48 hours. Millipedes do not bite but may secrete a toxin that is irritating, particularly when accidentally rubbed into the ...
Scorpion Stings
Feb 1, 2009
The stings of North American scorpions are rarely serious and usually result in pain, minimal swelling, tenderness, and warmth at the sting site. However, the bark scorpion (Centruroides exilicauda or sculpturatus), which is present in Arizona and Ne...
Marine Animal Stings and Bites
Feb 1, 2009
A variety of marine animals sting or bite....
Surgery
Feb 1, 2009
Surgery is the term traditionally used for treatments that involve cutting or stitching tissue. However, advances in surgical techniques have made the definition more complicated. Sometimes lasers, rather than scalpels, are used to cut tissue, and wo...
Overview of Complementary and Alternative Medicine
Feb 1, 2009
Complementary and alternative medicine (CAM) includes a variety of healing approaches and therapies that are taken from around the world and that historically have not been included in conventional Western medicine. Many aspects of CAM are rooted in ...
Whole Medical Systems
Feb 1, 2009
Whole medical systems are complete systems of diagnosis and practice. Examples are traditional Chinese medicine, Ayurveda, and unconventional Western practices of natural healing....
Mind-Body Techniques
Feb 1, 2009
Mind-body techniques are based on the theory that mental and emotional factors can influence physical health. Behavioral, psychologic, social, and spiritual methods are used to preserve health and prevent or cure disease....
Biologically Based Therapies
Feb 1, 2009
Biologically based therapies use naturally occurring substances and include individual biologic therapies (such as using shark cartilage to treat cancer and glucosamine to treat osteoarthritis), diet therapy, herbal medicine, orthomolecular medicine,...
Manipulative and Body-Based Therapies
Feb 1, 2009
Manipulative and body-based therapies treat various conditions through bodily manipulation. These therapies include chiropractic, massage, rolfing, reflexology, and postural reeducation....
Energy Therapies
Feb 1, 2009
Energy therapies focus on the energy fields thought to exist in and around the body (biofields). They also encompass the use of external energy sources (electromagnetic fields) to influence health and healing. All energy therapies are based on a core...
Travel Preparations
Feb 1, 2009
Travel preparation is crucial, even for healthy people. Proper preparations are inexpensive relative to the costs of getting sick or injured while away from home....
Problems in Transit
Feb 1, 2009
Several conditions are common even among healthy people while in transit....
Specific Medical Conditions and Travel
Feb 1, 2009
People with certain medical conditions encounter special problems in transit....
Medical Problems at the Destination
Feb 1, 2009
Problems after arrival are especially important to prevent and avoid in international settings. Though many people are most concerned about infection when considering a trip overseas, heart disease is the most common cause of death among internationa...
Medical Problems After Travel
Feb 1, 2009
Symptoms or problems that develop during travel and that do not subside by the time a person returns home warrant medical attention....
Overview of Medicinal Herbs and Neutraceuticals
Feb 1, 2009
Medicinal herbs are plant parts, sometimes ground, extracted, or otherwise prepared, used for health benefits. Nutraceuticals, a more recent and more general term, are a group of natural substances that includes certain herbs and ...
Black Cohosh
Feb 1, 2009
Black cohosh is a plant. The underground stem of this plant is available in powder, tablet, or liquid form....
Chamomile
Feb 1, 2009
The daisy-like flower of this herb is dried and used as tea or in an extract....
Chondroitin Sulfate
Feb 1, 2009
Chondroitin sulfate is a natural component of cartilage. It is extracted from shark or cow cartilage or manufactured synthetically. It is frequently combined with glucosamine....
Chromium
Feb 1, 2009
Chromium is a mineral required in small quantities by the body. It enables insulin to function. Whole-grain products are good sources of chromium. Picolinate is often paired with chromium in supplements....
Coenzyme Q10
Feb 1, 2009
Coenzyme Q10 (ubiquinone) is an enzyme that is naturally produced in the body. It participates in the energy-managing processes of cells and has an antioxidant effect. Antioxidants protect cells against damage by free radicals, which are highly chemi...
Cranberry
Feb 1, 2009
Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices....
Creatine
Feb 1, 2009
Creatine is an amino acid made in the liver and stored in muscles. When combined with phosphate, it is a readily available source of energy in the body. In the diet, creatine is found in milk, red meat, and some fish....
Dehydroepiandrosterone (DHEA)
Feb 1, 2009
Dehydroepiandrosterone (DHEA) is a steroid produced in the adrenal glands and converted into sex hormones (estrogens and androgens). DHEA's effects on the body are similar to those of testosterone. DHEA can be extracted from the Mexican yam....
Echinacea
Feb 1, 2009
Echinacea is a perennial herb, which contains echinacoside and several other active substances. Various parts of the plant are used medicinally....
Feverfew
Feb 1, 2009
Feverfew is a bushy perennial herb. The dried leaves are used in capsules, tablets, and liquid extracts. Parthenolide and glycosides are thought to be its active components....
Fish Oil
Feb 1, 2009
Fish oil may be extracted directly or concentrated and put in capsule form. Active ingredients are omega-3 fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]). Western diets typically are low in omega-3 fatty acids....
Garlic
Feb 1, 2009
Garlic has long been used in cooking and in medicine. When a garlic bulb is cut or crushed, an amino acid byproduct called allicin is released. Allicin is responsible for garlic's strong odor and medicinal properties....
Ginger
Feb 1, 2009
Like garlic, ginger has long been used in cooking and in medicine. The stem of this herb contains substances called gingerols, which give ginger its flavor and odor....
Ginkgo
Feb 1, 2009
Ginkgo is derived from the leaves of the ginkgo tree (commonly planted for ornamental purposes). The leaves contain numerous biologically active substances. Ginkgo is one of the most commonly used herbal supplements....
Ginseng
Feb 1, 2009
Ginseng is usually derived from two different species of plant: American ginseng and Asian ginseng. American ginseng is milder than Asian ginseng. Ginseng is available in many forms, such as fresh and dried roots, extracts, solutions, capsules, table...
Glucosamine
Feb 1, 2009
Glucosamine is extracted from a material (chitin) present in the shells of crabs, oysters, and shrimp. Glucosamine is taken in tablet or capsule form, usually as glucosamine sulfate, but sometimes as glucosamine hydrochloride. Glucosamine often is ta...
Goldenseal
Feb 1, 2009
Goldenseal, an endangered plant, is related to the buttercup. Its active components are hydrastine and berberine, which have antiseptic activity. Berberine is also active against diarrhea....
Green Tea
Feb 1, 2009
Green tea is made from the dried leaves of the same plant as traditional tea. However, traditional tea leaves are fermented, and green tea leaves are steamed but unfermented. Green tea may be brewed and drunk or ingested in tablet or capsule form. It...
Kava
Feb 1, 2009
Kava comes from the root of a shrub that grows in the South Pacific. It is ingested as a tea or in capsule form....
Licorice
Feb 1, 2009
Natural licorice, which has a very sweet taste, is extracted from the root of a shrub and used medicinally as a capsule, tablet, or liquid extract. Most licorice candy made in the United States is artificially flavored and does not contain natural li...
Melatonin
Feb 1, 2009
Melatonin, a hormone produced by the pineal gland (located in the middle of the brain), regulates the sleep-wake cycle. Melatonin used in supplements is derived from animals or produced artificially. In some countries, melatonin is considered a drug ...
Milk Thistle
Feb 1, 2009
The main active ingredient, silymarin, is found in the seeds of this prickly leafed, purple-flowered plant....
S-Adenosyl-L-Methionine (SAMe)
Feb 1, 2009
S-adenosyl-L-methionine (SAMe) is a naturally occurring agent in the human body and is manufactured synthetically as a supplement....
Saw Palmetto
Feb 1, 2009
The plant's berries can be made into tea. Saw palmetto is also available as tablets, capsules, and a liquid extract....
St. John's Wort
Feb 1, 2009
The reddish substance in the plant's flowers contains numerous biologically active compounds, including hypericin and hyperforin....
Valerian
Feb 1, 2009
The plant's dried root contains valepotriates, which may have calming effects....
Zinc
Feb 1, 2009
Zinc, a mineral, is required in small quantities for many metabolic processes. Dietary sources include oysters, beef, and fortified cereals....
Being Admitted to the Hospital
Feb 1, 2009
People are admitted to a hospital when they have a serious or life-threatening problem (such as a heart attack). They also may be admitted for less serious disorders that cannot be adequately treated in another place (such as at home or in an outpati...
Problems Due to Hospitalization
Feb 1, 2009
Just being in the hospital can cause certain problems, such as infections, pressure sores, and depression. Many hospital-related problems are caused by having to stay in bed for long periods. Others may result from being in unfamiliar surroundings or...
Being Discharged From the Hospital
Feb 1, 2009
When people have recovered sufficiently or can be appropriately treated elsewhere, they are discharged from the hospital. Staff members may ask questions to determine whether people are likely to need extra help after discharge. A discharge planner o...
The Older Driver
Feb 1, 2009
Driving provides a sense of freedom, independence, and involvement with the world that many people take for granted in their earlier adulthood. But the privilege of driving is based on the ability to drive safely. Drivers aged 70 and over are among t...
Overview of Long-Term Care
Feb 1, 2009
The prospect of needing long-term care services concerns many older people. The likelihood of needing long-term care increases greatly as people age. Older people are more likely to develop chronic disorders and to have problems functioning. Learning...
Care in the Home
Feb 1, 2009
Care in the home is usually provided by family members, friends, or both. If needed, health care practitioners, such as visiting nurses, therapists, and home health aides, may come to the home to provide additional care. Home care is often coordinate...
Retirement Communities
Feb 1, 2009
Retirement communities are designed for people who can live independently but who need or want some help, mainly with caring for a home. Some older people choose to move to a retirement community before they need additional help. They may move becaus...
Assisted Living Communities
Feb 1, 2009
Assisted living communities are designed for people who can care for themselves if they have some help with daily activities. These communities can help older people who have problems with memory, who get confused, or who have physical problems. Some...
Board-and-Care Facilities
Feb 1, 2009
Typically, board-and-care facilities are similar to assisted living communities. They are for people who need some help, particularly with personal care. Board-and-care facilities, sometimes also called rest homes, adult care homes, or personal care ...
Life-Care Communities
Feb 1, 2009
Life-care communities (also called continuing care retirement communities) are for older people who want to move only once, to a place that will provide as much care as they need for the rest of their life. These communities guarantee that residents ...
Nursing Homes
Feb 1, 2009
Nursing homes are for people who need help with health care for chronic conditions but do not need to be hospitalized. The decision to move to a nursing home may be triggered by a change in circumstances. A disorder may suddenly worsen, or an injury ...
Overview of Elder Mistreatment (Elder Abuse)
Feb 1, 2009
Elder mistreatment refers to harm or the threat of harm to an older person by another person. It includes abuse and neglect.
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Types of Elder Mistreatment
Feb 1, 2009
Older people may be abused, neglected, or both....
Prevention of Elder Mistreatment
Feb 1, 2009
Older people who are worried about mistreatment can take steps to make it less likely to happen, such as the following:...
Responding to Elder Mistreatment
Feb 1, 2009
Older people should never think that mistreatment is part of being old or dependent. Being mistreated threatens their personal dignity and sense of well-being and can even cost people their life....
Overview of Health Care Coverage for Older People
Feb 1, 2009
Dealing with the costs of a serious or chronic disorder can be as distressing as dealing with the disorder itself. The costs are often beyond the personal resources of most people. For older people, most health care expenses are paid for by the follo...
Medicare
Feb 1, 2009
Medicare is a health insurance program that helps older people pay for health care services. It is funded by the federal government. About 45 million people are covered by Medicare. Of these, 38 million are age 65 and older and 7 million are younger ...
Medigap
Feb 1, 2009
Medigap is supplemental insurance designed to pay for medical care not covered by Medicare, including the deductibles and copayments required by Medicare and extra charges by doctors who do not accept Medicare as full payment for a service. To obtain...
Medicaid
Feb 1, 2009
Medicaid is a program funded jointly by the federal and state governments to help pay for health care. It is intended for people of all ages who have a very low income and few assets. Eligibility requirements for Medicaid vary from state to state. Pe...
Aging and Drugs
Feb 1, 2009
Drugs, the most common medical intervention, are an important part of medical care for older people. Without drugs, many older people would function less well or die at an earlier age....
Introduction
Jan 1, 2009
The most common problems in adolescents relate to growth and development; childhood illnesses that continue into adolescence; mental health disorders; and the consequences of risky or illegal behaviors, including injury, legal consequences, pregnancy...
Delayed Puberty
Jan 1, 2009
Delayed puberty is defined as absence of the onset of sexual maturation at the expected time.
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Early Puberty
Jan 1, 2009
Precocious puberty and pseudoprecocious puberty are sexual maturation that begins before age 9 in a boy or before age 7 or 8 in a girl.
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Short Stature
Jan 1, 2009
Short stature is defined as height below the 3rd percentile for the child's age (according to standard charts for age and height).
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Obesity in Adolescents
Jan 1, 2009
Obesity is defined as a body mass index (BMI) greater than the 95th percentile for age and gender.
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School Problems in Adolescents
Jan 1, 2009
School constitutes a large part of an adolescent's existence. Difficulties in almost any area of life often manifest as school problems....
Behavioral Problems in Adolescents
Jan 1, 2009
Adolescence is a time for developing independence. Typically, adolescents exercise their independence by questioning their parents' rules, which at times leads to rule breaking. Parents and doctors must distinguish occasional errors of judgment from ...
Drug and Substance Use and Abuse in Adolescents
Jan 1, 2009
Substance use among adolescents ranges from experimentation to dependence (see ). The consequences range from none to minor to life threatening, depending on the substance, the circumstances, and the frequency of use. However, even occasional use can...
Contraception and Adolescent Pregnancy
Jan 1, 2009
Many adolescents engage in sexual activity but may not be fully informed about contraception, pregnancy, and sexually transmitted diseases, including human immunodeficiency virus (HIV) infection. Impulsivity, lack of planning, and concurrent drug and...
Introduction
Jan 1, 2009
Ear, nose, and throat disorders, particularly infections, are extremely common among children....
Middle Ear Infections in Young Children
Jan 1, 2009
Middle ear infection is infection of the space immediately behind the eardrum.
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Secretory Otitis Media in Children
Jan 1, 2009
Secretory otitis media (serous otitis media) is fluid accumulation behind the eardrum (see ).
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Pharyngitis (Sore Throat) in Children
Jan 1, 2009
Pharyngitis is infection of the throat (pharynx) and sometimes the tonsils.
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Enlarged Tonsils and Adenoids
Jan 1, 2009
Tonsils and adenoids are collections of lymphoid tissue that help the body fight infection. They trap bacteria and viruses entering through the throat and produce antibodies. The tonsils are located on both sides of the back of the throat. The adenoi...
Hearing Impairment in Children
Jan 1, 2009
Hearing impairment is relatively common among children:...
Objects in the Ears and Nose
Jan 1, 2009
Cotton, pieces of pencils, paper, pebbles, and beans are just a few of the many objects children put in their ears and nose. Insects sometimes crawl into ears and cause substantial pain....
Neck Masses in Children
Jan 1, 2009
Neck masses are swellings that change the shape of the neck.
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Laryngeal Papillomas
Jan 1, 2009
Laryngeal papillomas are rare noncancerous (benign) tumors of the voice box (larynx).
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Juvenile Angiofibroma
Jan 1, 2009
Juvenile angiofibroma is a rare noncancerous (benign) tumor that grows in the back of the nose, in the same area where the adenoids are (see ).
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Communication Disorders in Children
Jan 1, 2009
A communication disorder can involve hearing, voice, speech, language, or a combination.
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Overview of Hereditary Periodic Fever Syndromes
Jan 1, 2009
Hereditary periodic fever syndromes are hereditary disorders that periodically cause episodes of fever and other symptoms that are not due to usual childhood infections or any other obvious disorder. The more common of these syndromes include...
Familial Mediterranean Fever
Jan 1, 2009
Familial Mediterranean fever is a hereditary disorder characterized by episodes of high fever with abdominal pain or, less commonly, chest pain, joint pain, or a rash.
...
PFAPA Syndrome
Jan 1, 2009
PFAPA (periodic fevers with aphthous stomatitis, pharyngitis, and adenitis) syndrome causes recurrent episodes of fever that last 3 to 6 days, mouth sores (stomatitis), a sore throat (pharyngitis), and swollen lymph glands (adenitis). It typ...
Overview of Childhood Cancer
Jan 1, 2009
Cancer is rare among children, occurring in only 1 of 5,000 children every year. The most common childhood cancers are leukemia (see ), brain tumors, and lymphoma (see ). Leukemia is responsible for about 33% of cases of childhood cancer, brain tumor...
Brain Tumors in Children
Jan 1, 2009
Brain tumors (see also ) are the second most common cancer in children younger than 15 years (after leukemia) and the second leading cause of death from cancer. What causes brain tumors is usually unknown....
Neuroblastoma
Jan 1, 2009
Neuroblastoma is a common childhood cancer that grows in parts of the nervous system.
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Retinoblastoma
Jan 1, 2009
Retinoblastoma is a cancer of the retina, the light-sensing area at the back of the eye.
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Rhabdomyosarcoma
Jan 1, 2009
Rhabdomyosarcoma is a fast-growing cancer that can develop in soft tissues (such as muscle) almost anywhere in the body.
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Wilms' Tumor
Jan 1, 2009
Wilms' tumor (nephroblastoma) is a specific kind of kidney cancer.
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Overview of Electrical Injuries
Jan 1, 2009
Injuries can result from spontaneous atmospheric electricity (lightning injuries) or generated electricity, such as household or industrial electrical currents (electrical injuries). Electrical current passing through the body generates heat, which b...
Electrical Injuries
Jan 1, 2009
An electrical injury occurs when a current passes through the body, interfering with the function of an internal organ or sometimes burning tissue.
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Lightning Injuries
Jan 1, 2009
A lightning injury occurs after brief exposure to the very intense current of the strike.
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Drowning
Jan 1, 2009
Drowning occurs when submersion in liquid causes suffocation or interferes with breathing.
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Overview of Poisoning
Jan 1, 2009
Poisoning is the harmful effect that occurs when a toxic substance is swallowed, is inhaled, or comes in contact with the skin, eyes, or mucous membranes, such as those of the mouth or nose.
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Acetaminophen Poisoning
Jan 1, 2009
More than 100 products contain acetaminophen, a common over-the-counter pain reliever that is also present in many combination prescription drugs. If several similar products are consumed at a time, a person may inadvertently take too much acetaminop...
Aspirin Poisoning
Jan 1, 2009
Ingestion of aspirin and similar drugs (salicylates) can lead to rapid poisoning due to an overdose. The dose necessary to cause acute poisoning, however, is quite large. A person weighing about 150 pounds would have to consume more than 30 325-milig...
Carbon Monoxide Poisoning
Jan 1, 2009
Carbon monoxide is a colorless, odorless gas that, when inhaled, prevents the blood from carrying oxygen and prevents the tissues from using oxygen effectively. Small amounts are not usually harmful, but poisoning occurs if levels of carbon monoxide ...
Caustic Substances Poisoning
Jan 1, 2009
Caustic substances (strong acids and alkalis), when swallowed, can burn the tongue, mouth, esophagus, and stomach. These burns may cause perforation (piercing) of the esophagus or stomach. Food and saliva leaking from a perforation cause severe, some...
Hydrocarbon Poisoning
Jan 1, 2009
Petroleum products, cleaning products, and glues contain hydrocarbons (substances composed largely of hydrogen and carbon). Many children younger than age 5 are poisoned by swallowing petroleum products, such as gasoline, kerosene, and paint thinners...
Insecticide Poisoning
Jan 1, 2009
The properties that make insecticides deadly to insects can sometimes make them poisonous to humans. Most serious insecticide poisonings result from the organophosphate and carbamate types of insecticides, particularly when used in suicide attempts. ...
Iron Poisoning
Jan 1, 2009
Pills containing iron are commonly used to treat certain kinds of anemia. Iron also is included in many multiple vitamin supplements. People—especially toddlers—who overdose on these pills may develop iron poisoning. Because many households contain a...
Lead Poisoning
Jan 1, 2009
Although it is far less common since paint containing lead pigment was banned in 1978 and lead was eliminated from most gasoline, lead poisoning (plumbism) is still a major public health problem in cities on the East Coast of the United States....
Overview of Drug Abuse
Jan 1, 2009
Drugs are an integral part of everyday life for many people—legitimately and illegitmately—and drug use among adolescents remains high (see )....
Alcohol
Jan 1, 2009
About 45 to 50% of adults currently drink alcohol, 20% are former drinkers, and 30 to 35% are lifetime abstainers. Drinking large amounts of alcohol (more than 2 to 6 drinks per day) for extended periods can damage a number of organs, especially the ...
Amphetamines
Jan 1, 2009
Amphetamines include amphetamine and its many variants such as methamphetamine (speed or crystal meth) and methylenedioxymethamphetamine (MDMA, Ecstasy, or Adam). Methamphetamine is the most commonly used amphetamine in the United States. Use of MDMA...
Anabolic Steroids
Jan 1, 2009
Anabolic steroids include the hormone testosterone and related drugs. Anabolic steroids have many physical effects, including promoting muscle growth and increasing strength and energy. Thus, these drugs are often used illegitimately to gain a compet...
Antianxiety and Sedative Drugs
Jan 1, 2009
Prescription drugs used to treat anxiety (antianxiety drugs) and induce sleep (sedatives or sleep aids) can cause dependence. These drugs include benzodiazepines (such as diazepam and lorazepam) and barbiturates. Each works in a different way, and ea...
Cocaine
Jan 1, 2009
Cocaine has effects similar to those of amphetamines. It may be snorted, injected directly into a vein, or heated and inhaled. When boiled with sodium bicarbonate, cocaine is converted into a freebase form called crack cocaine. Heating crack cocaine ...
Gamma Hydroxybutyrate
Jan 1, 2009
Gamma hydroxybutyrate (GHB or G) is taken by mouth. It is similar to ketamine or alcohol in its effects, but its effects last longer and GHB is much more dangerous....
Hallucinogens
Jan 1, 2009
Hallucinogens include LSD (lysergic acid diethylamide), psilocybin (mushroom), mescaline (peyote), dimethyltryptamine (DMT), and 2,5-dimethoxy-4-methylamphetamine (DOM or STP), an amphetamine derivative. Many new compounds are being synthesized, and ...
Ketamine
Jan 1, 2009
Ketamine is a drug used for anesthesia. People who use it illicitly may snort it or inject it intravenously, into a muscle, or under the skin....
Marijuana
Jan 1, 2009
Marijuana (cannabis) use is widespread. Surveys of high school students have shown periodic variation in its use....
Nicotine
Jan 1, 2009
Nicotine is the substance in tobacco (present in cigarettes, cigars, and pipe and chewing tobacco) that users become dependent on. It is also the active ingredient in some drug products used to help people quit smoking....
Opioids
Jan 1, 2009
Opioids have a legitimate medical use as powerful pain relievers (see ). They include codeine (which has a low potential for dependence), oxycodone (alone and in various combinations, such as oxycodone plus acetaminophen), meperidine, morphine, penta...
Phencyclidine
Jan 1, 2009
Phencyclidine (PCP or angel dust) is most often smoked after being sprinkled on plant material, such as parsley, mint leaves, tobacco, or marijuana. Occasionally, PCP is taken by mouth or injected....
Solvent Inhalants
Jan 1, 2009
Adolescents use inhalants more frequently than cocaine or LSD but less frequently than marijuana or alcohol. In the United States, about 10% of adolescents have inhaled solvents. Inhalant use is particularly a problem among children aged 12 and young...
Introduction
Jan 1, 2009
Providing medical care to older people can be complicated. People often have many different doctors at different locations. Travel and transportation issues become more difficult as people age. The drugs that are covered by the new Medicare prescript...
Continuity of Care
Jan 1, 2009
Continuity of care is an ideal in which health care is provided for a person in a coordinated manner and without disruption despite involvement of different practitioners in different care settings. Also, all people involved in a person's health care...
Care Providers: Practitioners
Jan 1, 2009
People, particularly older people, often need to see several types of health care practitioners. Sometimes a group of health care practitioners work together to provide care. This type of care is called interdisciplinary care (see )....
Care Providers: Family and Friends
Jan 1, 2009
Some older people have family members, friends, or neighbors who are willing and able to provide help and care. Such people may be called caregivers. Occasionally, members of religious or other groups help or take over the role of caregiver altogethe...
Settings for Care
Jan 1, 2009
Health care practitioners may provide care for older people in a variety of settings....
Falls in the Elderly
Jan 1, 2009
Many older people fear falling. And they have good reason to do so. Falls are common among older people. About one third of older people who live at home fall at least once a year, and people who live in a nursing home fall even more often....
Chronic Obstructive Pulmonary Disease
Dec 1, 2008
Chronic obstructive pulmonary disease is persistent obstruction of the airways occurring with emphysema, chronic bronchitis, or both disorders.
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Alpha1-Antitrypsin Deficiency
Dec 1, 2008
Alpha1-antitrypsin deficiency is a hereditary disorder in which a lack or low level of the enzyme alpha1-antitrypsin damages the lungs and liver.
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Overview of Menstrual Disorders
Dec 1, 2008
Complex interactions among hormones control the start of menstruation during puberty, the rhythms and duration of menstrual cycles during the reproductive years, and the end of menstruation at menopause. ...
Premenstrual Syndrome
Dec 1, 2008
Premenstrual syndrome (PMS) is a group of physical and psychologic symptoms that start several days before and usually end a few hours after a menstrual period begins.
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Dysmenorrhea
Dec 1, 2008
Dysmenorrhea is pain in the lowest part of the abdomen (pelvis) during a menstrual period.
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Amenorrhea
Dec 1, 2008
Amenorrhea is the absence of menstrual periods.
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Dysfunctional Uterine Bleeding
Dec 1, 2008
Dysfunctional uterine bleeding is abnormal bleeding resulting from changes in the hormonal control of menstruation.
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Polycystic Ovary Syndrome
Dec 1, 2008
Polycystic ovary syndrome involves disruption of the menstrual cycle and a tendency to have high levels of male hormones (androgens).
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Fibroids
Dec 1, 2008
A fibroid is a noncancerous tumor composed of muscle and fibrous tissue.
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Pelvic Floor Disorders
Dec 1, 2008
Pelvic floor (pelvic support) disorders involve a dropping down (prolapse) of the bladder, urethra, small intestine, rectum, uterus, or vagina caused by weakness of or injury to the ligaments, connective tissue, and muscles of the pelvis.
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Definition of High-Risk Pregnancy
Dec 1, 2008
There is no formal or universally accepted definition of a “high-risk” pregnancy. Generally, however, a high-risk pregnancy involves at least one of the following:...
Risk Factors Present Before Pregnancy
Dec 1, 2008
Some risk factors are present before women become pregnant. These risk factors include certain physical and social characteristics of women, problems that have occurred in previous pregnancies, and certain disorders women already have....
Risk Factors That Develop During Pregnancy
Dec 1, 2008
During pregnancy, a problem may occur or a condition may develop to make the pregnancy high risk. For example, pregnant women may be exposed to something that can cause birth defects (teratogens), such as radiation, certain chemicals, drugs, or infec...
Overview of Labor and Delivery
Dec 1, 2008
Although each labor and delivery is different, most follow a general pattern. Therefore, an expectant mother can have a general idea of what changes will occur in her body to enable her to deliver the baby and what procedures will be followed to help...
Labor
Dec 1, 2008
Labor is a series of rhythmic, progressive contractions of the uterus that gradually move the fetus through the lower part of the uterus (cervix) and birth canal (vagina) to the outside world.
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Delivery
Dec 1, 2008
Delivery is the passage of the fetus and placenta (afterbirth) from the uterus to the outside world.
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Labor and Timing Problems
Dec 1, 2008
No more than 10% of women deliver on their specified due date (usually estimated to be about 40 weeks of pregnancy). About 50% of women deliver within 1 week (before or after), and almost 90% deliver within 2 weeks of the due date....
Fetus or Newborn Problems During Delivery
Dec 1, 2008
If labor does not proceed normally, the fetus or newborn may have problems....
Problems Affecting the Woman During Delivery
Dec 1, 2008
Some complications of pregnancy also cause problems during labor or delivery. For example, preeclampsia (see ), which involves high blood pressure accompanied by protein in the urine, can develop any time from the 20th week of pregnancy through the 6...
Labor and Delivery Procedures
Dec 1, 2008
Induction of labor is the artificial starting of labor. Usually, labor is induced by giving the woman oxytocin, a hormone that makes the uterus contract more frequently and more forcefully. The oxytocin given...
Introduction
Dec 1, 2008
Noncancerous (benign) gynecologic growths include cysts, polyps, and myomas. Noncancerous growths can develop on the vulva or in the vagina, uterus, or ovaries. Occasionally, cysts or tumors in an ovary can cause the ovary to twist—a disorder called ...
Adnexal Torsion
Dec 1, 2008
Adnexal torsion is twisting of the ovary and sometimes the fallopian tube, cutting off the blood supply of these organs.
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Cervical Myomas
Dec 1, 2008
Cervical myomas are smooth, benign tumors in the cervix.
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Cervical Stenosis
Dec 1, 2008
Cervical stenosis is narrowing of the passageway through the cervix (the lower part of the uterus).
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Gynecologic Cysts
Dec 1, 2008
Cysts are closed sacs that are separate from the tissue around them. They often contain fluid or semisolid material. Cysts that commonly occur in the genital organs include Bartholin's gland cysts, endometriomas, inclusion and epidermal cysts, and Sk...
Noncancerous Ovarian Growths
Dec 1, 2008
Noncancerous (benign) ovarian growths include functional cysts and tumors.
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Polyps of the Cervix
Dec 1, 2008
Cervical polyps are common fingerlike growths of tissue that protrude into the passageway through the cervix. Polyps are almost always benign (noncancerous).
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Overview of Disease During Pregnancy
Dec 1, 2008
Certain disorders, such as diabetes and high blood pressure, can increase the risk of problems during pregnancy. If women who have such a disorder wish to become pregnant, they should first talk with a doctor and try to get in the best physical condi...
Anemia During Pregnancy
Dec 1, 2008
Anemia develops in most pregnant women to some degree. The most common cause is an iron deficiency....
Asthma During Pregnancy
Dec 1, 2008
The effect of pregnancy on asthma varies. Worsening of the disease is slightly more common than improvement, but most pregnant women do not have severe asthma attacks. The effect of asthma on pregnancy also varies, but risk of preterm delivery and po...
Autoimmune Disorders During Pregnancy
Dec 1, 2008
Autoimmune disorders, including Graves' disease (see ), are more common among women, particularly pregnant women. The abnormal antibodies produced in autoimmune disorders can cross the placenta and cause problems in the fetus. Pregnancy affects diffe...
Cancer During Pregnancy
Dec 1, 2008
Because cancer tends to be life threatening and because delays in treatment may reduce the likelihood of successful treatment, cancer is usually treated the same way whether the woman is pregnant or not. Some of the usual treatments (surgery, chemoth...
Diabetes During Pregnancy
Dec 1, 2008
For women who have diabetes before they become pregnant, the risks of complications during pregnancy depend on how long diabetes has been present and whether complications of diabetes, such as high blood pressure and kidney damage, are present....
Fevers During Pregnancy
Dec 1, 2008
A temperature higher than 103° F (39.5° C) during the 1st trimester increases the risk of a miscarriage and defects of the brain or spinal cord in the baby. Fever late in pregnancy increases the risk of preterm labor....
Fibroids During Pregnancy
Dec 1, 2008
Fibroids in the uterus (see ), which are relatively common noncancerous tumors, may increase the risk of preterm labor, abnormal presentation of the fetus, a mislocated placenta (placenta previa), and repeated miscarriages. Rarely, fibroids interfere...
Heart Disorders During Pregnancy
Dec 1, 2008
Most women who have heart disorders—including heart valve disorders (such as mitral valve prolapse) and some birth defects of the heart—can safely give birth to healthy children, without any permanent ill effects on heart function or life span. Howev...
High Blood Pressure During Pregnancy
Dec 1, 2008
High blood pressure (hypertension) during pregnancy is classified as one of the following:...
Infections During Pregnancy
Dec 1, 2008
Most common infections that occur during pregnancy, such as those of the skin and respiratory tract, cause no serious problems. However, some infections can be passed to the fetus before or during birth and damage the fetus or cause a miscarriage or ...
Kidney Disorders During Pregnancy
Dec 1, 2008
Women with a severe kidney disorder before pregnancy are more likely to have problems during pregnancy. If high blood pressure develops, kidney function may rapidly worsen during pregnancy. High blood pressure commonly occurs in people with a kidney ...
Liver and Gallbladder Disorders During Pregnancy
Dec 1, 2008
Women who have chronic viral hepatitis or scarring of the liver (cirrhosis) are more likely to miscarry or to give birth prematurely. Cirrhosis can cause varicose veins to develop around the esophagus (esophageal varices). Pregnancy slightly increase...
Seizure Disorders During Pregnancy
Dec 1, 2008
Women who have seizures are slightly more likely to develop preeclampsia (a type of high blood pressure that develops during pregnancy) and to have a stillbirth or a fetus who does not grow as much as expected. On the other hand, taking anticonvulsan...
Disorders That Require Surgery During Pregnancy
Dec 1, 2008
During pregnancy, a disorder that requires surgery involving the abdomen may develop. This type of surgery often slightly increases the risk of preterm labor and can cause a miscarriage, especially early in pregnancy. Thus, surgery is usually delayed...
Thromboembolic Disorders During Pregnancy
Dec 1, 2008
In the United States, thromboembolic disorders are the leading cause of death in pregnant women. In thromboembolic disorders, blood clots form in blood vessels. They may travel through the bloodstream and block an artery. The risk of developing a thr...
Thyroid Disorders During Pregnancy
Dec 1, 2008
Thyroid disorders may be present before women become pregnant, or they may develop during pregnancy. Being pregnant does not change the symptoms of thyroid disorders. How the fetus is affected depends on which thyroid disorder is present and which dr...
Urinary Tract Infections During Pregnancy
Dec 1, 2008
Urinary tract infections are common during pregnancy, probably because the enlarging uterus and hormones slow the flow of urine in the tubes that connect the kidneys to the bladder (ureters). When urine flow is slow, bacteria may not be flushed out o...
Introduction
Dec 1, 2008
Pregnancy complications are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. For example, complications such as a mislocated placenta (placenta previa) or ...
Problems With Amniotic Fluid
Dec 1, 2008
Amniotic fluid is the fluid that surrounds the fetus in the uterus. The fluid and fetus are contained in membranes called the amniotic sac. There may be too much or too little amniotic fluid....
Cervical Incompetence
Dec 1, 2008
Cervical incompetence is painless opening of the cervix that results in delivery of the baby between 16 and 22 weeks of pregnancy.
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Ectopic Pregnancy
Dec 1, 2008
Ectopic pregnancy is attachment (implantation) of a fertilized egg in an abnormal location.
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Hyperemesis Gravidarum
Dec 1, 2008
Hyperemesis gravidarum is extremely severe nausea and excessive vomiting during pregnancy.
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Miscarriage
Dec 1, 2008
A miscarriage (spontaneous abortion) is the loss of a fetus due to natural causes before 20 weeks of pregnancy.
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Stillbirth
Dec 1, 2008
Stillbirth is death and delivery of a fetus after 20 weeks of pregnancy.
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Placenta Previa
Dec 1, 2008
Placenta previa is attachment (implantation) of the placenta over or near the cervix, in the lower rather than the upper part of the uterus.
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Placental Abruption (Abruptio Placentae)
Dec 1, 2008
Placental abruption (abruptio placentae) is the premature detachment of a normally positioned placenta from the wall of the uterus.
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Preeclampsia
Dec 1, 2008
Preeclampsia is high blood pressure that is accompanied by protein in the urine and that develops after the 20th week of pregnancy.
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Rh Incompatibility
Dec 1, 2008
Rh incompatibility occurs when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood.
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Overview of Chromosomal Disorders
Dec 1, 2008
Chromosomes are structures within cells that contain a person's genes. A gene is a segment of DNA and contains the code for a specific protein that functions in one or more types of cells in the body (see for a discussion about genetics)....
Down Syndrome (Trisomy 21; Trisomy G)
Dec 1, 2008
Down syndrome (trisomy 21, trisomy G) is a chromosomal disorder resulting in mental retardation/intellectual disability and physical abnormalities.
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Fragile X Syndrome
Dec 1, 2008
Fragile X syndrome is a genetic abnormality in the X chromosome that leads to delayed development and other symptoms.
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Turner's Syndrome
Dec 1, 2008
In Turner's syndrome (gonadal dysgenesis), girls are born with one of their two X chromosomes partially or completely missing.
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Noonan's Syndrome
Dec 1, 2008
Noonan's syndrome is a genetic defect that causes a number of physical abnormalities, including short stature, heart defects, and an abnormal appearance.
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Triple X Syndrome
Dec 1, 2008
Triple X (trisomy X, XXX) syndrome is a rare disorder in which female infants are born with three X chromosomes.
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Klinefelter's Syndrome
Dec 1, 2008
Klinefelter's syndrome is a disorder in which male infants are born with an extra X chromosome (XXY).
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XYY Syndrome
Dec 1, 2008
The XYY syndrome is a disorder in which a male infant is born with an extra Y chromosome.
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Long QT Syndrome
Dec 1, 2008
Long QT syndrome is an abnormality of the heart's electrical system (see ), which may cause loss of consciousness or sudden death.
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Overview of Fractures
Dec 1, 2008
A fracture is a crack or break in a bone, usually accompanied by injury to the surrounding tissues.
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Foot and Ankle Fractures
Dec 1, 2008
Fractures of the foot bones are common and are caused by falls, twisting injuries, or direct impact of the foot against hard objects. Foot fractures cause considerable pain, which is almost always made worse by attempting to walk or put weight on the...
Leg Fractures
Dec 1, 2008
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Hip Fractures
Dec 1, 2008
More than 270,000 hip fractures occur in the United States each year, with about 90% of them occurring in people older than 60. Hip fractures are more common in older people because of osteoporosis and because older people are more likely to fall. Us...
Pelvis Fractures
Dec 1, 2008
The pelvis is made up of pairs of large broad (iliac) bones in the back joined by two smaller connecting bone struts (the pubic and ischial rami) in the front. In young adults, major fractures of the entire pelvis can occur as a result of high-speed ...
Compression Fractures of the Spine
Dec 1, 2008
In a compression fracture of the spine, the cylindrical-shaped part of the back bone (vertebra) that makes up the column of the spine and bears most of the weight, becomes compressed into a wedge shape. These fractures usually occur in older people, ...
Rib Fractures
Dec 1, 2008
Rib fractures usually result from a strong force, such as falls, motor vehicle accidents, or a hit with a baseball bat. However, sometimes in older people, only a slight force (such as a minor fall) is required. The fracture itself is rarely serious,...
Clavicle Fractures
Dec 1, 2008
Clavicle fractures occur commonly after a fall on an outstretched arm or after a direct blow. Because the clavicle lies just under the skin and has little muscle covering, swelling and deformity are easily seen after a fracture. Most of these injurie...
Humerus Fractures
Dec 1, 2008
Fractures of the upper arm bone (humerus) usually occur near the shoulder. These fractures are common after a fall on an outstretched arm or after a direct blow. Symptoms include pain and an inability to raise the arm. Fractures of the middle of the ...
Elbow Fractures
Dec 1, 2008
Elbow fractures can involve any of the three bones that make up the joint (radius, ulna, and humerus). Fractures of the radial head or neck (the upper end of the radius) occur commonly in active adults after a fall on an outstretche...
Wrist Fractures
Dec 1, 2008
Wrist fractures involve the radius, and sometimes also the ulna. Certain types of wrist fractures are called Colles' fractures.These occur commonly after a fall on an outstretched arm, particularly in older people. People h...
Hand Fractures
Dec 1, 2008
Hand fractures involve the bones that form part of the wrist (carpals), bones of the palm (metacarpals), or bones of the fingers and thumb (phalanges). Normal hand function results from a complex interaction of an intricate arrangement of muscles, te...
Introduction
Dec 1, 2008
Many people have disorders for which no specific cause has been identified. Some doctors believe that some of these disorders of unknown cause are due to psychologic factors. Others believe that the disorders are caused by infections (such as viral i...
Chronic Fatigue Syndrome
Dec 1, 2008
Chronic fatigue syndrome refers to long-standing severe and disabling fatigue without a proven physical or psychologic cause.
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Gulf War Syndrome
Dec 1, 2008
Gulf War syndrome consists of a group of symptoms experienced by more than 100,000 American, British, and Canadian veterans of the 1992 Persian Gulf War.
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Multiple Chemical Sensitivity Syndrome
Dec 1, 2008
Multiple chemical sensitivity syndrome seems to be triggered by exposure to low levels of several identifiable or unidentifiable substances commonly present in the environment.
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Introduction
Dec 1, 2008
As people grow older, they face many changes. With aging, the ability to do daily activities (functional ability) declines to some degree in every person. Also, older people, on average, tend to have more disorders and disability than do younger peop...
Life-Changing Events Related to Aging
Dec 1, 2008
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Aging and Staying Connected
Dec 1, 2008
Studies have shown that people who remain active and who interact with other people during old age live longer, happier, healthier lives. Volunteering, taking classes, joining social groups, engaging in hobbies, and pursuing some type of spiritual or...
Overview of Retinal Disorders
Nov 1, 2008
The cornea and lens focus light onto the retina, the transparent, light-sensitive membrane on the inner surface of the back of the eye. The central area of the retina, called the macula, contains a high density of color-sensitive photoreceptor (light...
Age-Related Macular Degeneration
Nov 1, 2008
Age-related macular degeneration (also called age-related maculopathy) causes progressive damage to the macula, the central and most vital area of the retina, resulting in gradual loss of central vision.
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Epiretinal Membrane
Nov 1, 2008
Epiretinal membrane (also called cellophane maculopathy, macular pucker, or premacular fibrosis) is formation of a thin membrane over the retina, which interferes with vision.
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Detachment of the Retina
Nov 1, 2008
Retinal detachment is separation of the retina from the underlying layer to which it is attached.
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Retinitis Pigmentosa
Nov 1, 2008
Retinitis pigmentosa is a rare, progressive degeneration of the retina that eventually causes moderate to severe vision loss.
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Blockage of Central Retinal Arteries and Veins
Nov 1, 2008
A blood vessel in the retina may become blocked, causing sudden, painless loss of vision.
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Hypertensive Retinopathy
Nov 1, 2008
Hypertensive retinopathy is damage to the retina caused by high blood pressure.
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Diabetic Retinopathy
Nov 1, 2008
Diabetic retinopathy is damage to the retina as a result of diabetes.
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Endophthalmitis
Nov 1, 2008
Endophthalmitis is infection inside the eye.
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Cancers Affecting the Retina
Nov 1, 2008
Cancers affecting the retina usually occur in the choroid, a dense layer of blood vessels that supplies the retina. The choroid is sandwiched between the retina and the sclera (the outer white part of the eye). Because the retina depends on the choro...
Overview of Sexual Dysfunction in Women
Nov 1, 2008
Sexual dysfunction includes painful intercourse, painful contraction (spasm) of the vaginal muscles, or a problem with sexual desire, arousal, or orgasm that causes distress.
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Dyspareunia
Nov 1, 2008
Dyspareunia is pain when women try to begin sexual intercourse or pain during intercourse.
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Vaginismus
Nov 1, 2008
Vaginismus is involuntary contraction of muscles around the opening of the vagina in women with no abnormalities identified during examination. The tight muscle contraction makes sexual intercourse painful or impossible.
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Low Sexual Desire Disorder
Nov 1, 2008
Low sexual desire disorder (sexual desire/interest disorder) is lack of interest in sexual activity and sexual thoughts.
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Sexual Arousal Disorders
Nov 1, 2008
Sexual arousal disorders involve a lack of response to sexual stimulation—mental or emotional (subjective), physical (such as swelling, tingling, or throbbing in the genital area or vaginal wetness), or both.
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Orgasmic Disorder
Nov 1, 2008
Orgasmic disorder is lack of or delay in sexual climax (orgasm) even though sexual stimulation is sufficient and the woman is sexually aroused.
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Overview of Breast Disorders
Nov 1, 2008
Breast disorders may be noncancerous (benign) or cancerous (malignant). Most are noncancerous and not life threatening. Often, they do not require treatment. In contrast, breast cancer can mean loss of a breast or of life. Thus, for many women, breas...
Breast Cysts
Nov 1, 2008
Breast cysts are fluid-filled sacs that develop in the breast.
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Fibroadenomas
Nov 1, 2008
Fibroadenomas are small, solid, rubbery noncancerous lumps composed of fibrous and glandular tissue.
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Fibrocystic Changes
Nov 1, 2008
Fibrocystic changes (formerly called fibrocystic breast disease) include breast pain, cysts, and lumpiness that are not due to cancer.
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Breast Infection and Abscess
Nov 1, 2008
A breast infection (mastitis) is rare, except around the time of childbirth (see ) or after an injury or surgery. The most common symptom is a swollen, red area that feels warm and tender. An uncommon type of breast cancer called inflammatory breast ...
Breast Cancer
Nov 1, 2008
Breast cancer is the second most common cancer among women after skin cancer and, of cancers, is the second most common cause of death among women after lung cancer. In 2006, breast cancer was diagnosed in about 213,000 women in the United States. Ab...
Overview of Female Reproductive System Cancers
Nov 1, 2008
Cancers can occur in any part of the female reproductive system—the vulva, vagina, cervix, uterus, fallopian tubes, or ovaries. These cancers are called gynecologic cancers....
Cancer of the Uterus
Nov 1, 2008
Cancer of the uterus develops in the lining of the uterus (endometrium) and is thus also called endometrial cancer.
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Ovarian Cancer
Nov 1, 2008
Cancer of the ovaries (ovarian carcinoma) develops most often in women aged 50 to 70. This cancer eventually develops in about 1 of 70 women. In the United States, it is the second most common gynecologic cancer. However, more women die of ovarian ca...
Cervical Cancer
Nov 1, 2008
Cervical cancer develops in the cervix (the lower part of the uterus).
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Vulvar Cancer
Nov 1, 2008
Vulvar cancer, usually a skin cancer, develops in the area around the female genital organs.
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Vaginal Cancer
Nov 1, 2008
Cancer of the vagina, an uncommon cancer, is usually a squamous cell skin cancer (vaginal carcinoma), which typically develops in older women....
Fallopian Tube Cancer
Nov 1, 2008
Fallopian tube cancer develops in the tubes that lead from the ovaries to the uterus.
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Hydatidiform Mole
Nov 1, 2008
A hydatidiform mole is growth of an abnormal fertilized egg or an overgrowth of tissue from the placenta.
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Overview of Genetic Disorders
Nov 1, 2008
A big concern of prospective parents is whether their baby will be healthy. Some problems that occur in babies are due to genetic disorders. These disorders result from abnormalities in one or more genes or in chromosomes ( and ). Some abnormalities ...
Genetic Screening
Nov 1, 2008
Genetic screening is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder. Any couple can request genetic screening, but screening is particularly recommended when one or both partners know they ...
Prenatal Diagnostic Testing
Nov 1, 2008
Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic disorders. Some of these tests, such as ultrasonography and...
Overview of the Postpartum Period
Nov 1, 2008
The postdelivery (postpartum) period is the 6 weeks after delivery of a baby, when the mother's body returns to its prepregnancy state.
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Postpartum Infections
Nov 1, 2008
Immediately after delivery, the woman's temperature often increases. A temperature of 101° F (38.3° C) or higher during the first 12 hours after delivery could indicate an infection but may not. Nonetheless, in such cases, the woman should be evaluat...
Postpartum Blood Clots
Nov 1, 2008
The risk of developing blood clots (thrombophlebitis) is increased after delivery. Typically, blood clots occur in the legs or pelvis (a disorder called deep vein thrombosis—see ). Sometimes one of these clots breaks loose and travels through the blo...
Postpartum Thyroid Disorders
Nov 1, 2008
In 4 to 7% of women, the thyroid gland malfunctions during the first 6 months after delivery. Thyroid hormone levels may be high or low, usually temporarily. Women who have a family history of thyroid disorders or diabetes are particularly susceptibl...
Postpartum Depression
Nov 1, 2008
Postpartum depression is a feeling of extreme sadness and related psychologic disturbances during the first few weeks or months after delivery.
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Overview of Tooth Disorders
Oct 1, 2008
Common tooth disorders include cavities (caused by tooth decay), pulpitis, periapical abscess, impacted teeth, and malocclusion. Fractured, loosened, and knocked-out teeth are considered urgent dental problems (see ), as are some toothaches. Tooth de...
Cavities
Oct 1, 2008
Cavities (dental caries) are decayed areas in the teeth, the result of a process that gradually dissolves a tooth's hard outer surface (enamel) and progresses toward the interior.
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Pulpitis
Oct 1, 2008
Pulpitis is painful inflammation of the tooth pulp, the innermost part of the tooth that contains the nerves and blood supply.
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Periapical Abscess
Oct 1, 2008
A periapical abscess is a collection of pus, usually from an infection that has spread from a tooth to the surrounding tissues.
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Impacted Teeth
Oct 1, 2008
Impacted teeth are teeth that are unable to emerge (erupt) properly from the gum.
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Malocclusion
Oct 1, 2008
Malocclusion is an abnormal alignment of the teeth or upper and lower jaws that prevents the teeth from meeting properly.
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Introduction
Oct 1, 2008
Periodontal diseases inflame and destroy the structures surrounding and supporting the teeth, primarily the gums, the jawbones, and the outer layer of the tooth root.
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Gingivitis
Oct 1, 2008
Gingivitis is inflammation of the gums (gingivae).
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Periodontitis
Oct 1, 2008
Periodontitis (pyorrhea) is a severe form of gingivitis in which the inflammation of the gums extends to the supporting structures of the tooth.
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Trench Mouth
Oct 1, 2008
Trench mouth (Vincent's infection, acute necrotizing ulcerative gingivitis) is a painful, noncontagious infection of the gums, causing pain, fever, and sometimes fatigue.
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Gum Recession
Oct 1, 2008
Gum recession is the loss of gum tissue from the base of a tooth with exposure of the root surface.
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Toothaches
Oct 1, 2008
Most toothaches are caused by cavities (tooth decay). Some toothaches are caused by a tooth abscess or by inflammation of the gum around the crown of a tooth (pericoronitis). Much less commonly, toothaches result from inflammation of the nasal sinuse...
Fractured, Loosened, or Knocked-Out Teeth
Oct 1, 2008
The upper front teeth are prone to injury and fracture. A person who has brief, sharp pain while chewing or while eating something cold may have an incomplete fracture of a tooth. As long as the fracture is incomplete and part of the tooth has not sp...
Jaw Fracture
Oct 1, 2008
The term “jaw fracture” usually refers to fracture of the lower jaw (mandible). A fractured jaw causes pain and usually changes the way the teeth fit together. Often, the mouth cannot be opened wide, or it shifts to one side when opening or closing....
Jaw Dislocation
Oct 1, 2008
A dislocated jaw (dislocated mandible) generally is very painful. The mouth cannot be closed, and the jaw may be twisted to one side. A dislocated jaw is typically caused by the following:...
Complications After Dental Treatment
Oct 1, 2008
Swelling is common after certain dental procedures, particularly tooth extractions and periodontal surgery. Holding an ice pack—or better yet, a plastic bag of frozen peas or corn (which adapts to facial contours)—to the ch...
Overview of Infectious Disease
Oct 1, 2008
Microorganisms are tiny living creatures, such as bacteria and viruses. Microorganisms are present everywhere. Despite their overwhelming abundance, relatively few of the thousands of species of microorganisms invade, multiply, and cause dis...
Resident Flora
Oct 1, 2008
Healthy people live in harmony with most microorganisms that establish themselves on (colonize) the body. The microorganisms that usually occupy a particular body site are called the resident flora. Microorganisms that colonize people for hours to we...
Development of Infection
Oct 1, 2008
Infectious diseases are usually caused by microorganisms that invade the body and multiply. Invasion by most microorganisms begins when they adhere to cells in a person's body. Adherence is a very specific process, involving "lock-and-key" connection...
Defenses Against Infection
Oct 1, 2008
Physical barriers and the immune system defend the body against organisms that can cause infection. Physical barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid. Also, the normal flow of urine washes out microorganisms...
Prevention of Infection
Oct 1, 2008
Several measures help protect people against infection. Hand washing is an effective way of preventing the spread of infectious microorganisms from one person to another. Hand washing is particularly important for people who handle food or who have f...
Infections in People With Impaired Defenses
Oct 1, 2008
Many disorders, drugs, and other treatments can cause a breakdown in the body's natural defenses. Such a breakdown can lead to infections, which can even be caused by microorganisms that normally live harmlessly on or in the body. A breakdown can res...
Tuberculosis
Oct 1, 2008
Tuberculosis is a contagious infection caused by the airborne bacteria Mycobacterium tuberculosis.
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Leprosy
Oct 1, 2008
Leprosy (Hansen's disease) is a chronic infection caused by the bacteria Mycobacterium leprae. It results in damage primarily to the peripheral nerves (the nerves outside the brain and spinal cord), skin, testes, eyes, and mucous membranes o...
Overview of Fungal Infections
Oct 1, 2008
Fungi are neither plants nor animals. They were once thought to be plants but are now classified as their own kingdom. Some fungi, including yeasts such as Candida and molds such as aspergilli, can be seen only through a microscope. Others, including...
Aspergillosis
Oct 1, 2008
Aspergillosis is infection, usually of the lungs, caused by the fungus Aspergillus.
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Blastomycosis
Oct 1, 2008
Blastomycosis (North American blastomycosis, Gilchrist's disease) is infection, mainly of the lungs, caused by the fungus Blastomyces dermatitidis.
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Candidiasis
Oct 1, 2008
Candidiasis (candidosis, moniliasis, yeast infection) is infection caused by several species of Candida, especially Candida albicans.
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Coccidioidomycosis
Oct 1, 2008
Coccidioidomycosis (San Joaquin fever, valley fever) is infection, usually of the lungs, caused by the fungus Coccidioides immitis.
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Cryptococcosis
Oct 1, 2008
Cryptococcosis is infection caused by the fungus Cryptococcus neoformans.
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Histoplasmosis
Oct 1, 2008
Histoplasmosis is infection caused by the fungus Histoplasma capsulatum. It occurs mainly in the lungs but can sometimes spread throughout the body.
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Mucormycosis
Oct 1, 2008
Mucormycosis (zygomycosis) is infection caused by Mucorales molds.
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Paracoccidioidomycosis
Oct 1, 2008
Paracoccidioidomycosis (South American blastomycosis) is infection caused by the fungus Paracoccidioides brasiliensis.
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Sporotrichosis
Oct 1, 2008
Sporotrichosis is infection caused by the fungus Sporothrix schenckii.
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Human Immunodeficiency Virus Infection
Oct 1, 2008
HIV infections may be caused by one of two retroviruses, HIV-1 or HIV-2. HIV-1 has caused a worldwide epidemic, but HIV-2 tends to be limited to West Africa....
Overview of Sexually Transmitted Diseases
Oct 1, 2008
Sexually transmitted (venereal) diseases are infections that are typically, but not exclusively, passed from person to person through sexual contact.
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Chancroid
Oct 1, 2008
Chancroid is a sexually transmitted disease caused by the bacteria Haemophilus ducreyi, which causes painful genital sores.
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Chlamydial and Other Infections
Oct 1, 2008
Chlamydial infections include sexually transmitted diseases of the urethra and cervix that are caused by the bacteria Chlamydia trachomatis. Less commonly, other bacteria, such as Ureaplasma and mycoplasmas, cause infection of the urethra.
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Genital Warts
Oct 1, 2008
Genital warts (condylomata acuminata) are growths in or around the vagina, penis, or rectum caused by the human papillomavirus, which is sexually transmitted.
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Gonorrhea
Oct 1, 2008
Gonorrhea is a sexually transmitted disease caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, and throat or the membranes that cover the front part of the eye (conjunctiva and cornea).
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Granuloma Inguinale
Oct 1, 2008
Granuloma inguinale is a rare sexually transmitted disease that is caused by the bacteria Calymmatobacterium granulomatis and that leads to chronic inflammation and scarring of the genitals.
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Lymphogranuloma Venereum
Oct 1, 2008
Lymphogranuloma venereum is a sexually transmitted disease that is caused by Chlamydia trachomatis and that causes painful, swollen lymph glands in the groin and sometimes infection of the rectum.
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Syphilis
Oct 1, 2008
Syphilis is a sexually transmitted disease caused by the bacteria Treponema pallidum.
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Trichomoniasis
Oct 1, 2008
Trichomoniasis is a sexually transmitted infection of the vagina or urethra that is caused by the protozoa Trichomonas vaginalis and that causes vaginal irritation and discharge.
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Other Sexually Transmitted Diseases
Oct 1, 2008
Some bacteria (Shigella, Campylobacter, and Salmonella), viruses (hepatitis A, B, and C), and parasites (Giardia and some amebas) are sometimes transmitted during sexual intercourse, although they...
Pressure Sores
Oct 1, 2008
Pressure sores (bedsores, decubitus ulcers, pressure ulcers) are areas of skin damage resulting from a lack of blood flow due to pressure.
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Overview of Skin Pigment
Oct 1, 2008
Various shades and colors of human skin are created by the brown pigment, melanin. Without melanin, the skin would be pale white with varying shades of pink caused by the blood flowing through it. Fair-skinned people produce very li...
Albinism
Oct 1, 2008
Albinism is a rare hereditary disorder in which little or no melanin is formed.
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Vitiligo
Oct 1, 2008
Vitiligo is a disorder in which a localized loss of melanocytes causes patches of skin to turn white.
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Melasma
Oct 1, 2008
Melasma causes dark brown patches of pigmentation to appear on sun-exposed areas, usually the face.
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Introduction
Oct 1, 2008
Many viral infections—such as measles, chickenpox, and rubella—cause rashes, spots, or sores on the skin, as well as other symptoms. Herpesviruses often cause rashes and sores (see ). However, in two common viral infections, warts and molluscum conta...
Warts
Oct 1, 2008
Warts (verrucae) are small skin growths caused by any of 100 or more related human papillomaviruses.
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Molluscum Contagiosum
Oct 1, 2008
Molluscum contagiosum is infection of the skin by a poxvirus that causes flesh-colored or white smooth, waxy bumps.
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Overview of Skin Cancer
Oct 1, 2008
Skin cancer is the most common form of cancer in the United States. The three main types of skin cancer—basal cell carcinoma, squamous cell carcinoma, and melanoma—are caused, at least in part, by long-term sun exposure. Lymphoma can also de...
Basal Cell Carcinoma
Oct 1, 2008
Basal cell carcinoma is a cancer that originates in cells of the outer layer of skin (epidermis).
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Squamous Cell Carcinoma
Oct 1, 2008
Squamous cell carcinoma is cancer that originates in the squamous cells (keratinocytes).
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Melanoma
Oct 1, 2008
Melanoma is a cancer that originates in the pigment-producing cells of the skin (melanocytes).
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Kaposi's Sarcoma
Oct 1, 2008
Kaposi's sarcoma is a cancer that produces multiple flat pink, brown, or purple patches or bumps on the skin. It is caused by herpesvirus type 8.
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Paget's Disease of the Nipple
Oct 1, 2008
Paget's disease of the nipple is a rare type of skin cancer that originates in glands in or under the skin.
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Introduction
Oct 1, 2008
The cornea is the domed, transparent covering in the front of the eye that protects the iris and lens and helps focus light on the retina. It is composed of cells, protein, and fluid. The cornea looks fragile but is almost as stiff as a fingernail. H...
Superficial Punctate Keratitis
Oct 1, 2008
Superficial punctate keratitis is death of small groups of cells on the surface of the cornea.
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Corneal Ulcer
Oct 1, 2008
A corneal ulcer is an infected open sore on the cornea.
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Keratoconjunctivitis Sicca
Oct 1, 2008
Keratoconjunctivitis sicca (dry eye) is dryness of the conjunctiva and cornea.
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Keratomalacia
Oct 1, 2008
Keratomalacia (also called xerophthalmia or xerotic keratitis) is drying and clouding of the cornea due to vitamin A deficiency and insufficient protein and calories in the diet.
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Herpes Simplex Keratitis
Oct 1, 2008
Herpes simplex keratitis is infection of the cornea caused by herpes simplex virus.
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Herpes Zoster Ophthalmicus
Oct 1, 2008
Herpes zoster ophthalmicus is infection of the eye caused by varicella-zoster virus.
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Peripheral Ulcerative Keratitis
Oct 1, 2008
Peripheral ulcerative keratitis is inflammation and ulceration of the cornea that often occurs in people who have connective tissue disorders such as rheumatoid arthritis.
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Keratoconus
Oct 1, 2008
Keratoconus is a gradual change in the shape of the cornea that causes it to become irregular and cone-shaped.
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Bullous Keratopathy
Oct 1, 2008
Bullous keratopathy is a blister-like swelling of the cornea.
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Inflammation of the Penis
Oct 1, 2008
The foreskin of the penis and the glans penis (the cone-shaped end of the penis) can be inflamed....
Phimosis and Paraphimosis
Oct 1, 2008
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Urethral Stricture
Oct 1, 2008
A urethral stricture is scarring that narrows the urethra.
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Growths on the Penis
Oct 1, 2008
Growths on the penis are sometimes caused by infections. One example is syphilis (see ), which may cause flat pink or gray growths (condylomata lata). Also, certain viral infections can produce one or more small, firm, raised skin growths (genital wa...
Priapism
Oct 1, 2008
Priapism is a painful, persistent erection unaccompanied by sexual desire or excitement.
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Peyronie's Disease
Oct 1, 2008
Peyronie's disease is a fibrous thickening that contracts and deforms the penis, distorting the shape of an erection.
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Injuries to the Penis and Scrotum
Oct 1, 2008
Several types of injuries can affect the penis....
Testicular Cancer
Oct 1, 2008
Most testicular cancers develop in men younger than age 40. It is one of the most common cancers in young men. Among the types of cancer that develop in the testes are seminoma, teratoma, embryonal carcinoma, and choriocarcinoma....
Testicular Torsion
Oct 1, 2008
Testicular torsion is the twisting of a testis on its spermatic cord so that the testis's blood supply is blocked.
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Inguinal Hernia
Oct 1, 2008
An inguinal hernia is a protrusion of a piece of intestine through an opening in the abdominal wall in the groin.
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Epididymitis and Epididymo-orchitis
Oct 1, 2008
Epididymitis is inflammation of the epididymis (the coiled tube on top of the testis that provides the space and environment for sperm to mature), and epididymo-orchitis is inflammation of the epididymis and testes.
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Swelling in the Scrotum
Oct 1, 2008
The scrotum can swell for many reasons. Possible causes include cancer, testicular torsion (see ), inguinal hernia (see ), epididymitis (see ), hydrocele, edema, orchitis, spermatocele, and varicocele....
Introduction
Oct 1, 2008
The prostate gland lies just under the bladder and surrounds the tube that carries urine from the bladder (the urethra). It produces the fluid in the semen that nourishes sperm. Walnut-sized in young men, the prostate gland enlarges with aging. Three...
Benign Prostatic Hyperplasia (BPH)
Oct 1, 2008
Benign prostatic hyperplasia (benign prostatic hypertrophy) is a noncancerous (benign) enlargement of the prostate gland that can make urination difficult.
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Prostate Cancer
Oct 1, 2008
Among men in the United States, prostate cancer is the most common cancer and one of the most common causes of cancer death. The chance of developing prostate cancer increases with age and is greater for...
Prostatitis
Oct 1, 2008
Prostatitis is pain and swelling, inflammation, or both of the prostate gland.
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Overview of Infertility
Oct 1, 2008
Infertility is the inability of a couple to achieve a pregnancy after repeated intercourse without contraception for 1 year.
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Problems With Sperm
Oct 1, 2008
Sperm may be too few in number, move too slowly, or be structurally abnormal, or their passage out of the body may be blocked or disrupted.
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Problems With Ovulation
Oct 1, 2008
The ovaries do not release an egg each month (see ).
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Problems With the Fallopian Tubes
Oct 1, 2008
The fallopian tube may be blocked or damaged, preventing the egg from moving from the ovary to the uterus to be implanted.
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Problems With Mucus in the Cervix
Oct 1, 2008
If mucus in the cervix is abnormal, it may prevent sperm from entering the uterus or may promote the destruction of sperm.
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Problems With Eggs
Oct 1, 2008
The number of eggs may be low, or the quality may be poor.
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Unidentified Infertility Factors
Oct 1, 2008
Unidentified factors are considered the explanation for infertility when semen in the man and ovulation and fallopian tubes in the woman are normal.
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Assisted Reproductive Techniques
Oct 1, 2008
Assisted reproductive techniques involve manipulating sperm and eggs in a culture dish (in vitro) with the goal of producing an embryo.
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Overview of the Immune System
Sep 1, 2008
The immune system is designed to defend the body against foreign or dangerous cells or substances that invade it. Such invaders include microorganisms (commonly called germs, such as bacteria, viruses, and fungi), parasites (such as worms), cancer ce...
Innate Immunity
Sep 1, 2008
Innate (natural) immunity is so named because it is present at birth and does not have to be learned through exposure to an invader. It thus provides an immediate response to foreign cells. However, its components treat all foreign substances in much...
Acquired Immunity
Sep 1, 2008
Acquired (adaptive or specific) immunity is not present at birth. It is learned. As a person's immune system encounters foreign substances (antigens), the components of acquired immunity learn the best way to attack each antigen and begin to develop ...
Effects of Aging on the Immune System
Sep 1, 2008
The immune system changes throughout life. At birth, specific immunity is not fully developed. However, newborns have some antibodies, which crossed the placenta from the mother during pregnancy. These antibodies protect newborns against infections u...
Overview of Immunodeficiency Disorders
Sep 1, 2008
Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual.
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Ataxia-Telangiectasia
Sep 1, 2008
Ataxia-telangiectasia is a hereditary disorder characterized by incoordination, dilated capillaries, and increased susceptibility to infections.
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Chronic Granulomatous Disease
Sep 1, 2008
Chronic granulomatous disease is a hereditary immunodeficiency disorder in which phagocytes (a type of white blood cell) malfunction.
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Chronic Mucocutaneous Candidiasis
Sep 1, 2008
Chronic mucocutaneous candidiasis is a hereditary immunodeficiency disorder due to malfunction of T cells (lymphocytes).
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Common Variable Immunodeficiency
Sep 1, 2008
Common variable immunodeficiency is a congenital immunodeficiency disorder characterized by very low antibody (immunoglobulin) levels despite a normal number of B cells (lymphocytes).
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DiGeorge Syndrome
Sep 1, 2008
DiGeorge syndrome is a congenital immunodeficiency disorder in which the thymus gland is absent or underdeveloped at birth.
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Hyperimmunoglobulinemia E Syndrome
Sep 1, 2008
Hyperimmunoglobulinemia E syndrome (hyper-IgE syndrome, or Buckley syndrome) is a hereditary immunodeficiency disorder characterized by early onset of recurrent boils and pneumonia but with very high levels of immunoglobulin E (IgE) and norm...
Selective Immunoglobulin Deficiency
Sep 1, 2008
Selective immunoglobulin deficiency is a congenital immunodeficiency disorder resulting in a low level of one type (class) of antibody (immunoglobulin), even though the levels of other immunoglobulins are normal.
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Severe Combined Immunodeficiency
Sep 1, 2008
Severe combined immunodeficiency is a congenital immunodeficiency disorder resulting in low levels of antibodies (immunoglobulins) and no T cells (lymphocytes).
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Spleen Disorders and Immunodeficiency
Sep 1, 2008
The spleen is crucial to the function of the immune system. The spleen filters the blood, removing and destroying bacteria and other infectious organisms in the bloodstream. It also produces antibodies (immunoglobulins). For people whose spleen is ab...
Transient Hypogammaglobulinemia of Infancy
Sep 1, 2008
In transient hypogammaglobulinemia of infancy, production of normal amounts of antibodies (immunoglobulins) in infants is delayed.
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Wiskott-Aldrich Syndrome
Sep 1, 2008
Wiskott-Aldrich syndrome is a hereditary immunodeficiency disorder characterized by abnormal antibody (immunoglobulin) production, T-cell (lymphocyte) malfunction, a low platelet count, and eczema.
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X-Linked Agammaglobulinemia
Sep 1, 2008
X-linked agammaglobulinemia (Bruton's disease) is a hereditary immunodeficiency disorder due to an abnormality in the X chromosome. It results in few or no B cells (lymphocytes) and very low levels of antibodies (immunoglobulins).
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Overview of Allergic Reactions
Sep 1, 2008
Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance.
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Seasonal Allergies
Sep 1, 2008
Seasonal allergies result from exposure to airborne substances (such as pollens) that appear only during certain times of the year.
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Year-Round Allergies (Perennial Allergies)
Sep 1, 2008
Year-round (perennial) allergies result from exposure to airborne substances (such as house dust) that are present throughout the year.
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Food Allergy
Sep 1, 2008
A food allergy is an allergic reaction to a particular food.
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Mastocytosis
Sep 1, 2008
Mastocytosis is an uncommon abnormal accumulation of mast cells in the skin and sometimes in various other parts of the body.
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Physical Allergy
Sep 1, 2008
A physical allergy is an allergic reaction triggered by a physical stimulus.
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Exercise-Induced Allergic Reactions
Sep 1, 2008
Exercise-induced allergic reactions occur during or after exercise.
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Hives and Angioedema
Sep 1, 2008
Hives, also called urticaria, is a skin reaction characterized by pale, slightly elevated swellings (wheals) that are surrounded by a red area and have clearly defined borders. Angioedema is swelling of larger areas of tissue unde...
Anaphylactic Reactions
Sep 1, 2008
Anaphylactic reactions (anaphylaxis) are sudden, widespread, potentially severe and life-threatening allergic reactions.
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Overview of Transplantation
Sep 1, 2008
Transplantation is the removal of living, functioning cells, tissues, or organs from the body and then their transfer back into the same body or into a different body.
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Kidney Transplantation
Sep 1, 2008
For people of all ages who have irreversible kidney failure, kidney transplantation is a lifesaving alternative to dialysis. In the United States, more than 17,000 kidneys are transplanted each year. Over 95% of kidneys from living donors are functio...
Liver Transplantation
Sep 1, 2008
Liver transplantation is the only option for people whose liver no longer functions. A whole liver can be obtained only from a person who has died, but a living donor can provide a part of the liver. A donated liver can be stored for 8 to 15 hours. M...
Heart Transplantation
Sep 1, 2008
Heart transplantation is reserved for people who have severe heart failure and who cannot be treated effectively with drugs or other forms of surgery. In some medical centers, heart machines can keep people alive for weeks or months until a compatibl...
Lung and Heart-Lung Transplantation
Sep 1, 2008
Lung transplants are done for people whose lungs no longer function. Most recipients are people who have severe chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, α1-antitrypsin deficiency, and primary pulmonary hy...
Pancreas Transplantation
Sep 1, 2008
Pancreas transplantation is done for people with diabetes whose pancreas cannot make any insulin. It is a major operation, requiring a long incision in the abdomen and a general anesthetic. The recipient's pancreas is not removed. Typically, the oper...
Stem Cell Transplantation
Sep 1, 2008
Stem cells are unspecialized cells from which other more specialized cells can be derived. Stem cells obtained from embryos and fetuses are thought to be best because they are more likely to survive transplantation than those obtained from children o...
Transplantation of Other Organs
Sep 1, 2008
Skin grafts can be used in people who have lost large areas of skin—for example, because of extensive burns. Skin grafting is most successful when healthy skin is removed from one part of the body and grafted to another par...
Overview of Bacteria
Sep 1, 2008
Bacteria are microscopic, single-celled organisms. There are thousands of different kinds, and they live in every conceivable environment all over the world. They live in soil, seawater, and deep within the earth's crust. Some bacteria have ...
Actinomycosis
Sep 1, 2008
Actinomycosis is a chronic infection caused mainly by Actinomyces israelii, anaerobic bacteria that normally reside on the enamel of teeth, gums, tonsils, and membranes lining the intestines and vagina.
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Anthrax
Sep 1, 2008
Anthrax is a potentially fatal infection with Bacillus anthracis, which may affect the skin, the lungs, or, rarely, the digestive (gastrointestinal) tract.
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Bejel, Yaws, and Pinta
Sep 1, 2008
Bejel, yaws (frambesia), and pinta are infections caused by bacteria (called treponemal spirochetes) that are closely related to Treponema pallidum, which causes the sexually transmitted disease syphilis.
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Campylobacter Infections
Sep 1, 2008
Several species of Campylobacter (most commonly Campylobacter jejuni) can infect the digestive tract, often causing diarrhea.
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Cholera
Sep 1, 2008
Cholera is a serious infection of the intestine that is caused by the bacteria Vibrio cholerae and that causes severe diarrhea.
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Gas Gangrene
Sep 1, 2008
Gas gangrene (clostridial myonecrosis) is a life-threatening infection of muscle tissue caused mainly by the anaerobic bacteria Clostridium perfringens and several other species of clostridia.
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Klebsiella, Enterobacter, and Serratia Infections
Sep 1, 2008
Klebsiella, Enterobacter, and Serratia are closely related gram-negative bacteria that occasionally infect people in hospitals or in long-term care facilities.
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Escherichia coli Infections
Sep 1, 2008
Escherichia coli
(E. coli) is a group of gram-negative bacteria that normally reside in the intestine of healthy people, but some strains can cause infection.
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Haemophilus influenzae Infections
Sep 1, 2008
Haemophilus influenzae can cause infection in the respiratory tract, which can spread to other organs.
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Leptospirosis
Sep 1, 2008
Leptospirosis is a potentially serious disorder caused by Leptospira bacteria.
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Listeriosis
Sep 1, 2008
Listeriosis is infection caused by the gram-positive bacteria Listeria monocytogenes.
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Lyme Disease
Sep 1, 2008
Lyme disease is caused by the bacteria Borrelia burgdorferi, which is usually transmitted to people by deer ticks.
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Meningococcal Infections
Sep 1, 2008
Meningococcal infections are caused by Neisseria meningitidis (meningococci) and include meningitis and bloodstream infections.
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Plague
Sep 1, 2008
Plague is a severe infection caused by the gram-negative bacteria Yersinia pestis.
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Pneumococcal Infections
Sep 1, 2008
Pneumococcal infections are caused by the gram-positive bacteria Streptococcus pneumoniae (pneumococcus).
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Pseudomonas Infections
Sep 1, 2008
Pseudomonas infections are caused by any of several types of the gram-negative bacteria Pseudomonas, especially Pseudomonas aeruginosa.
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Salmonella Infections
Sep 1, 2008
Salmonella infections are caused by the gram-negative bacteria Salmonella.
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Shigellosis
Sep 1, 2008
Shigellosis is infection that is caused by the gram-negative bacteria Shigella and that results in watery diarrhea or dysentery (the frequent and often painful passage of small amounts of stool that contains blood, pus, and mucus).
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Staphylococcus aureus Infections
Sep 1, 2008
Staphylococcus aureus is the most dangerous of all of the many common staphylococcal bacteria.
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Streptococcal Infections
Sep 1, 2008
Streptococcal infections are caused by any one of several species of Streptococcus.
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Tetanus
Sep 1, 2008
Tetanus (lockjaw) results from a toxin produced by the anaerobic bacteria Clostridium tetani. The toxin makes muscles become rigid and contract involuntarily (spasm).
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Toxic Shock Syndrome
Sep 1, 2008
Toxic shock syndrome is a group of rapidly progressive and severe symptoms that include fever, rash, dangerously low blood pressure, and failure of several organs. It is caused by toxins produced by Staphylococcus aureus or group A streptoco...
Tularemia
Sep 1, 2008
Tularemia (rabbit fever, deer fly fever) is infection that is caused by the bacteria Francisella tularensis, which is acquired from wild animals, usually rabbits.
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Introduction
Sep 1, 2008
Bacteremia, sepsis, and septic shock are related:...
Bacteremia
Sep 1, 2008
Bacteremia is the presence of bacteria in the bloodstream (see also ).
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Sepsis and Septic Shock
Sep 1, 2008
Sepsis is a serious bodywide response to bacteremia or another infection. Septic shock is life-threatening low blood pressure (shock) due to sepsis.
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Antibiotics
Sep 1, 2008
Antibiotics (antibacterials) are drugs derived wholly or partially from bacteria or molds and are used to treat bacterial infections. They are ineffective against viral infections (see ) and fungal infections (see ). Antibiotics either kill microorga...
Overview of Blistering Disorders
Sep 1, 2008
A blister (bulla) is a bubble of fluid that forms beneath a thin layer of dead skin. The fluid is a mixture of water and proteins that oozes from injured tissue. Blisters most commonly form in response to a specific injury, such as a burn or irritati...
Bullous Pemphigoid
Sep 1, 2008
Bullous pemphigoid is an autoimmune disease that causes blistering of the skin.
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Dermatitis Herpetiformis
Sep 1, 2008
Dermatitis herpetiformis is an autoimmune disease causing clusters of intensely itchy small blisters and hivelike swellings.
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Pemphigus Vulgaris
Sep 1, 2008
Pemphigus vulgaris is a rare, severe autoimmune disease in which blisters of varying sizes break out on the skin, the lining of the mouth, the genitals, and other mucous membranes.
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Scabies
Sep 1, 2008
Scabies is a mite infestation of the skin that produces tiny reddish bumps and severe itching.
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Lice Infestation
Sep 1, 2008
Lice infestation (pediculosis) is a skin infestation by tiny wingless insects.
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Cutaneous Larva Migrans
Sep 1, 2008
Cutaneous larva migrans (creeping eruption) is a hookworm infection transmitted from warm, moist soil to exposed skin.
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Cutaneous Myiasis
Sep 1, 2008
Cutaneous myiasis is skin infestation by the larvae (maggots) of certain fly species.
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Overview of Skin Growths
Sep 1, 2008
Cells of the skin and underlying tissue may accumulate and cause growths. Growths may be raised or flat and range in color from dark brown or black to flesh-colored to red. They may be present at birth or develop later....
Moles
Sep 1, 2008
Moles (nevi) are small, usually dark, skin growths that develop from pigment-producing cells in the skin (melanocytes).
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Skin Tags
Sep 1, 2008
Skin tags are soft, small, flesh-colored or slightly darker skin growths that develop mostly on the neck, in the armpits, or in the groin area.
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Lipomas
Sep 1, 2008
Lipomas are soft deposits of body fat that grow under the skin, causing round or oval lumps.
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Dermatofibromas
Sep 1, 2008
Dermatofibromas are small red-to-brown bumps (nodules) that result from an accumulation of collagen, which is a protein made by the cells (fibroblasts) that populate the soft tissue under the skin.
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Growths and Malformations of the Vessels
Sep 1, 2008
Growths and malformations of the vessels (angiomas) are collections of abnormally dense blood or lymph vessels, usually located in and below the skin, that cause red or purple discolorations.
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Seborrheic Keratoses
Sep 1, 2008
Seborrheic keratoses (seborrheic warts) are warty, flesh-colored, brown, or black growths that can appear anywhere on the skin.
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Keratoacanthomas
Sep 1, 2008
Keratoacanthomas are round, firm, usually flesh-colored or slightly reddish growths that have a central crater that is scaly or crusted.
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Keloids
Sep 1, 2008
Keloids are smooth, shiny, flesh-colored, raised growths of scar-like tissue that form over areas of injury or surgical wounds.
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Epidermal Cysts
Sep 1, 2008
An epidermal cyst is a common slow-growing bump due to an enlarging sac under the skin that accumulates a cheesy substance composed of skin secretions.
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Introduction
Sep 1, 2008
The eye sockets (orbits) are bony cavities that contain and protect the eyes and their supporting structures. Disorders affecting the orbits include fractures (see ), infections, inflammation, vascular disorders, and tumors. Thyroid disease can also ...
Infections of the Orbit
Sep 1, 2008
Infections may involve the tissues around or within the eye. These infections are most common among children....
Inflammation of the Orbit
Sep 1, 2008
Any or all of the structures within the orbit may become inflamed....
Tumors of the Orbit
Sep 1, 2008
Rarely, tumors, either cancerous (malignant) or noncancerous (benign), occur in the tissues behind the eye. Tumors can form within these tissues, or cancerous tumors from elsewhere in the body can spread (metastasize) to these tissues....
Proptosis
Sep 1, 2008
Proptosis (exophthalmos) is an abnormal bulging of one or both eyes.
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Overview of Vaginal Infections
Sep 1, 2008
In the United States, vaginal infections are one of the most common reasons women see their doctor, accounting for more than 10 million visits each year. Vaginal infections can cause discomfort, discharge, and vaginal odor. However, these symptoms do...
Bacterial Vaginosis
Sep 1, 2008
Bacterial vaginosis is a vaginal infection that occurs when the balance of bacteria in the vagina is altered.
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Trichomonas Vaginitis
Sep 1, 2008
Trichomonas vaginitis is a vaginal infection due to the protozoa Trichomonas vaginalis.
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Vaginal Yeast Infection (Candidiasis)
Sep 1, 2008
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Pelvic Inflammatory Disease (PID)
Sep 1, 2008
Pelvic inflammatory disease is an infection of the upper female reproductive organs.
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Overview of Minerals
Aug 1, 2008
Minerals are necessary for the normal functioning of the body's cells. The body needs large quantities of calcium, chloride, magnesium, phosphate, potassium, and sodium. These minerals are called macrominerals. Bone, muscle, heart, and brain function...
Chromium
Aug 1, 2008
Chromium enables insulin (which controls blood sugar levels) to function and helps in the processing (metabolism) and storage of carbohydrates, protein, and fat. Only a small amount of the chromium in food is absorbed. Chromium is absorbed better whe...
Copper
Aug 1, 2008
Most of the copper in the body is located in the liver, bones, and muscle, but traces of copper occur in all tissues of the body. The liver excretes excess copper into the bile for elimination from the body. Copper is a component of many enzymes, inc...
Fluoride
Aug 1, 2008
In the body, most fluoride is contained in bones and teeth. Fluoride is necessary for the formation and health of bones and teeth....
Iodine
Aug 1, 2008
The thyroid gland contains most of the iodine in the body. Iodine in the thyroid gland is necessary for the formation of thyroid hormones. Iodine occurs in seawater. A small amount of iodine enters the atmosphere and, through rain, enters ground wate...
Iron
Aug 1, 2008
Much of the iron in the body is contained in hemoglobin. Hemoglobin is the component of red blood cells that enables them to carry oxygen and deliver it to the body's tissues. Iron also is an important component of muscle cells. It is also necessary ...
Molybdenum
Aug 1, 2008
Molybdenum is required for processing (metabolizing) nitrogen, activating certain enzymes, and enabling cells to function normally. Molybdenum also helps break down sulfites (which occur in foods naturally and are added as preservatives)....
Selenium
Aug 1, 2008
Selenium occurs in all tissues. Selenium works with vitamin E as an antioxidant. It helps protect cells against damage by free radicals, which are reactive by-products of normal cell activity. Selenium may help protect against some cancers. Selenium ...
Zinc
Aug 1, 2008
Zinc is widely distributed in the body—in bones, teeth, hair, skin, liver, muscle, white blood cells, and testes. It is a component of more than 100 enzymes, including those involved in the formation of RNA (ribonucleic acid) and DNA (deoxyribonuclei...
Obesity
Aug 1, 2008
Obesity is the accumulation of excessive body fat.
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Bariatric Surgery
Aug 1, 2008
Bariatric surgery alters the stomach, intestine, or both to produce weight loss.
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Metabolic Syndrome
Aug 1, 2008
Metabolic syndrome (also called syndrome X or insulin resistance syndrome) is characterized by excess abdominal fat, resistance to the effects of insulin (insulin resistance), abnormal levels of fats in the blood, and high blood pressure.
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Overview of Cholesterol and Lipid Disorders
Aug 1, 2008
Cholesterol and triglycerides are important fats (lipids) in the blood. Cholesterol is an essential component of cell membranes, brain and nerve cells, and bile, which helps the body absorb fats and fat-soluble vitamins. The body uses choles...
Dyslipidemia
Aug 1, 2008
Dyslipidemia is abnormal levels of lipids (cholesterol, triglycerides, or both) carried by lipoproteins in the blood. This term includes hyperlipoproteinemia (hyperlipidemia), which refers to abnormally high levels of total cholesterol, low ...
Hypolipoproteinemia
Aug 1, 2008
Hypolipoproteinemia is abnormally low levels of lipids in the blood.
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About Body Water
Aug 1, 2008
Water accounts for about one half to two thirds of an average person's weight. Fat tissue has a lower percentage of water and women tend to have more fat, so the percentage of water in the average woman is lower (52 to 55%) than it is in the average ...
Dehydration
Aug 1, 2008
Dehydration is a deficiency of water in the body.
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Overhydration
Aug 1, 2008
Overhydration is an excess of water in the body.
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Electrolytes
Aug 1, 2008
Some minerals—especially the macrominerals—are important as electrolytes. The body uses electrolytes to help regulate nerve and muscle function and to maintain acid-base balance (see ) and water balance ()....
Sodium
Aug 1, 2008
Most of the body's sodium is located in blood and in the fluid around cells. Sodium helps the body keep fluids in a normal balance (see ). Sodium plays a key role in normal nerve and muscle function....
Potassium
Aug 1, 2008
Most of the body's potassium is located inside the cells. Potassium is necessary for the normal functioning of cells, nerves, and muscles....
Calcium
Aug 1, 2008
About 99% of the body's calcium is stored in the bones, but cells (particularly muscle cells) and blood also contain calcium. Calcium is essential for the following:...
Magnesium
Aug 1, 2008
Bone contains most of the body's magnesium. Blood contains very little. Magnesium is necessary for the formation of bone and teeth and for normal nerve and muscle function. Many enzymes in the body depend on magnesium to function normally. The body o...
Phosphate
Aug 1, 2008
In the body, almost all phosphorus is combined with oxygen, forming phosphate. Bone contains about 85% of the body's phosphate. The rest is located primarily inside cells, where it is involved in energy production....
Overview of Porphyria
Aug 1, 2008
Porphyrias are a group of disorders caused by deficiencies of enzymes involved in the production of heme.
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Porphyria Cutanea Tarda
Aug 1, 2008
Porphyria cutanea tarda is the most common porphyria and causes blistering and fragility of skin exposed to sunlight.
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Acute Intermittent Porphyria
Aug 1, 2008
Acute intermittent porphyria, which causes abdominal pain and neurologic symptoms, is the most common acute porphyria.
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Erythropoietic Protoporphyria
Aug 1, 2008
Erythropoietic protoporphyria is a condition characterized by photosensitivity.
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Overview of Cancer
Aug 1, 2008
A cancer is an abnormal growth of cells (usually derived from a single cell). The cells have lost normal control mechanisms and thus are able to expand continuously, invade adjacent tissues, migrate to distant parts of the body, and promote the growt...
Development and Spread of Cancer
Aug 1, 2008
Cancerous cells develop from healthy cells in a complex process called malignant transformation....
Risk Factors for Cancer
Aug 1, 2008
Many genetic and environmental factors increase the risk of developing cancer. However, not all people who are exposed to carcinogens or who have other risk factors develop cancer....
Defenses Against Cancer
Aug 1, 2008
Even when a cell becomes cancerous, the immune system is thought to be able to recognize it as abnormal and destroy it before it replicates or spreads. Cancer is more likely to progress in people whose immune system is altered or impaired, as in peop...
Acne
Aug 1, 2008
Acne is a common skin condition causing pimples on the face and upper torso.
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Overview of Hair Growth
Aug 1, 2008
Hair originates in the hair follicles. These follicles are located in the dermis, the skin layer just below the surface layer and above the subcutaneous fat. Hair follicles are present everywhere on the surface of the body except th...
Hirsutism and Hypertrichosis
Aug 1, 2008
Hirsutism is the excessive growth of thick or dark hair in women in locations that are more typical of male hair patterns (for example, mustache, beard, central chest, shoulders, lower abdomen, back, and inner thighs). Hypertricho...
Alopecia
Aug 1, 2008
Alopecia is the loss of hair on the head or on any other part of the body.
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Ingrown Beard Hairs
Aug 1, 2008
Ingrown beard hairs (pseudofolliculitis barbae) is inflammation caused by hairs that curl so that the tips puncture the skin.
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Overview of Fungal Skin Infections
Aug 1, 2008
Fungi usually make their homes in moist areas of the body where skin surfaces meet: between the toes, in the genital area, and under the breasts. Many fungi that infect the skin (dermatophytes) live only in the topmost layer of the epidermis (stratum...
Candidiasis
Aug 1, 2008
Candidiasis (yeast infection, moniliasis) is infection by the yeast Candida.
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Ringworm (Tinea)
Aug 1, 2008
Ringworm (tinea) is a fungal skin infection caused by several different fungi and generally classified by its location on the body.
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Tinea Versicolor
Aug 1, 2008
Tinea versicolor (pityriasis versicolor) is a fungal infection of the topmost layer of the skin causing scaly, discolored patches.
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Glaucoma
Aug 1, 2008
Glaucoma is optic nerve damage (often, but not always, associated with increased eye pressure) that leads to progressive, irreversible loss of vision.
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Cystic Fibrosis
Aug 1, 2008
Cystic fibrosis is a hereditary disease that causes certain glands to produce abnormal secretions, resulting in tissue and organ damage, especially in the lungs and the digestive tract.
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Overview of Cold Injuries
Aug 1, 2008
The skin and the tissues under it are kept at a constant temperature (about 98.6° F, or 37°C) by the circulating blood and other mechanisms. The blood gets its heat mainly from the energy given off by cells when they burn (metabolize) food—a...
Hypothermia
Aug 1, 2008
Hypothermia is a dangerously low body temperature.
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Nonfreezing Tissue Injuries
Aug 1, 2008
In nonfreezing tissue injuries, parts of the skin are chilled but not frozen.
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Frostbite
Aug 1, 2008
Frostbite is a cold injury in which an area of the body is frozen.
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Temporomandibular Disorders
Jul 1, 2008
The temporomandibular joints are the connections between the temporal bones of the skull and the lower jawbone (mandible). There are two temporomandibular joints, one on each side of the face just in front of the ears. Ligaments, tendons, and muscles...
Overview of Nutrition
Jul 1, 2008
Nutrition is the process of consuming, absorbing, and using nutrients needed by the body for growth, development, and maintenance of life.
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Carbohydrates, Proteins, and Fats
Jul 1, 2008
Carbohydrates, proteins, and fats supply 90% of the dry weight of the diet and 100% of its energy. All three provide energy (measured in calories), but the amount of energy in 1 gram (1/28 ounce) differs: 4 calories in a gram of carbohydrate or prote...
Vitamins and Minerals
Jul 1, 2008
Vitamins and minerals are essential nutrients. That is, they cannot be synthesized by the body and so must be consumed in the diet....
Fiber
Jul 1, 2008
Some foods contain fiber, which is a tough complex carbohydrate. Fiber may be partly soluble: It dissolves in water, and the body may be able to digest some of it. Or it may be insoluble: It does not dissolve in water, and the body cannot digest it. ...
Food Additives and Contaminants
Jul 1, 2008
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Calories
Jul 1, 2008
A calorie is a measure of energy. Foods have calories. That is, foods supply the body with energy, which is released when foods are broken down during digestion. Energy enables cells to do all of their functions, including building proteins and other...
Nutritional Requirements
Jul 1, 2008
General guidelines for a healthy diet have been developed even though daily nutritional requirements, including those for essential nutrients, vary depending on age, sex, height, weight, physical activity, and the rate at which the body burns calorie...
Diets
Jul 1, 2008
A diet is whatever a person eats, regardless of the goal—whether it is losing weight, gaining weight, reducing fat intake, avoiding carbohydrates, or having no particular goal. However, the term is often used to imply a goal of losing weight, which i...
Overview of Plasma Cell Disorders
Jul 1, 2008
Plasma cell disorders (plasma cell dyscrasias) are uncommon. They begin when a single group (clone) of plasma cells multiplies excessively and produces a large quantity of a single type of antibody (immunoglobulin). Plasma cells develop from B lympho...
Monoclonal Gammopathies of Undetermined Significance
Jul 1, 2008
A monoclonal gammopathy of undetermined significance is a buildup of monoclonal antibodies produced by abnormal but noncancerous plasma cells.
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Multiple Myeloma
Jul 1, 2008
Multiple myeloma is a cancer of plasma cells in which abnormal plasma cells multiply uncontrollably in the bone marrow and occasionally in other parts of the body.
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Macroglobulinemia
Jul 1, 2008
Macroglobulinemia (Waldenström's macroglobulinemia) is a plasma cell cancer in which a single clone of plasma cells produces excessive amounts of a certain type of large antibody (IgM) called macroglobulins.
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Heavy Chain Diseases
Jul 1, 2008
Heavy chain diseases are plasma cell cancers in which a clone of plasma cells produces a large quantity of pieces of abnormal antibodies called heavy chains.
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Overview of Lymphoma
Jul 1, 2008
Lymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs.
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Hodgkin Lymphoma
Jul 1, 2008
Hodgkin lymphoma is a type of lymphoma distinguished by the presence of a particular kind of cancer cell called a Reed-Sternberg cell.
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Non-Hodgkin Lymphomas
Jul 1, 2008
Non-Hodgkin lymphomas are a diverse group of cancers that develop in B or T lymphocytes.
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Overview of Myeloproliferative Disorders
Jul 1, 2008
In myeloproliferative disorders (myelo = bone marrow, proliferative = rapid multiplication), the blood-producing cells in the bone marrow (precursor cells) develop and reproduce excessively or are crowded out by an overgrowth of fibrous tissue. Typic...
Polycythemia Vera
Jul 1, 2008
Polycythemia vera (primary polycythemia) is a disorder of the blood-producing cells of the bone marrow that results in overproduction of red blood cells.
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Myelofibrosis
Jul 1, 2008
Myelofibrosis is a disorder in which fibrous tissue replaces the blood-producing cells in the bone marrow, resulting in abnormally shaped red blood cells, anemia, and an enlarged spleen.
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Thrombocythemia
Jul 1, 2008
Thrombocythemia (primary thrombocythemia) is a disorder in which excess platelets are produced, leading to abnormal blood clotting or bleeding.
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Overview of Acid-Base Balance
Jul 1, 2008
An important property of blood is its degree of acidity or alkalinity. Body acidity increases when the level of acidic compounds in the body rises (through increased intake or production, or decreased elim...
Acidosis
Jul 1, 2008
Acidosis is excessive blood acidity caused by an overabundance of acid in the blood or a loss of bicarbonate from the blood (metabolic acidosis), or by a buildup of carbon dioxide in the blood that results from poor lung function or slow bre...
Alkalosis
Jul 1, 2008
Alkalosis is excessive blood alkalinity caused by an overabundance of bicarbonate in the blood or a loss of acid from the blood (metabolic alkalosis), or by a low level of carbon dioxide in the blood that results from rapid or deep breathing...
Overview of Immunization
Jul 1, 2008
Immunization enables the body to better defend itself against diseases caused by certain bacteria or viruses. Immunization may occur on its own (when people are exposed to bacteria or viruses), or doctors may provide it. When people are immunized aga...
Common Vaccinations
Jul 1, 2008
Children typically are given a number of vaccines according to a standard schedule (see ). If vaccines are missed, most can be given later, according to a catch-up schedule. Adults may also be advised to receive certain vaccines. When advising adults...
Vaccination Before Foreign Travel
Jul 1, 2008
Residents of the United States may be required to receive specific vaccines before traveling to areas that have infectious diseases not normally found in the United States (see ). Recommendations change frequently in response to disease outbreaks. Th...
Ear Blockages
Jul 1, 2008
Earwax (cerumen) may block the ear canal. Even large amounts of earwax often cause no symptoms. Symptoms can range from itching to a loss of hearing. A doctor may remove the earwax by gently flushing out the ear canal with ...
External Otitis
Jul 1, 2008
External otitis is infection of the ear canal.
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Perichondritis
Jul 1, 2008
Perichondritis is infection of the tissue surrounding the cartilage of the earlobe (pinna), ear canal, or both.
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Ear Tumors
Jul 1, 2008
Tumors of the ear may be noncancerous (benign) or cancerous (malignant). Most ear tumors are found when people see them or when a doctor looks in the ear because people notice their hearing seems decreased....
Injury to the Ear
Jul 1, 2008
A number of different injuries can affect the outer ear. A blunt blow to the external ear can cause bruising between the cartilage and the layer of connective tissue around it (perichondrium). When blood collects in this area, the external ear become...
Introduction
Jul 1, 2008
The upper part of the nose consists mostly of bone. The lower part of the nose gains its support from cartilage. Inside the nose is a hollow cavity (nasal cavity), which is divided into two passages by a thin sheet of cartilage and bone called the na...
Fractures of the Nose
Jul 1, 2008
The bones of the nose are broken (fractured) more often than any other facial bone. When nasal bones break, the mucous membrane lining the nose usually tears, resulting in a nosebleed. Most commonly, the bridge of the nose is pushed to one side. Some...
Deviated Septum
Jul 1, 2008
Usually, the nasal septum is straight, lying about in the middle of the two nostrils. Occasionally, it may be bent (deviated) because of a birth defect or injury and positioned so that one nostril is much smaller than the other. Most people have some...
Perforations of the Septum
Jul 1, 2008
Ulcers and holes (perforations) in the nasal septum may occur as a result of nasal surgery; repeated injury such as that resulting from picking the nose; cosmetic piercing; exposure to toxins (such as acids, chromium, phosphorus, and copper vapor); c...
Nosebleeds
Jul 1, 2008
Nosebleeds (epistaxis) have a variety of causes, the most common of which are nose picking and injury. The cold, dry air of winter also makes nosebleeds more likely. People who take aspirin or other drugs that interfere with the blood's ability to cl...
Nasal Vestibulitis
Jul 1, 2008
Nasal vestibulitis is infection of the area just inside the opening of each nostril (the nasal vestibule).
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Rhinitis
Jul 1, 2008
Rhinitis is inflammation and swelling of the mucous membrane of the nose, characterized by a runny nose and stuffiness and usually caused by the common cold (see ) or an allergy (see ).
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Nasal Polyps
Jul 1, 2008
Nasal polyps are fleshy outgrowths of the mucous membrane of the nose.
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Sinusitis
Jul 1, 2008
Sinusitis is inflammation of the sinuses, most commonly caused by a viral or bacterial infection or by an allergy.
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Smell and Taste Disorders
Jul 1, 2008
Because disorders of smell and taste are rarely life threatening, they may not receive close medical attention. Yet, these disorders can be frustrating because they can affect the ability to enjoy food and drink and to appreciate pleasant aromas. The...
Introduction
Jul 1, 2008
Disorders of the throat (pharynx) and voice box (larynx) may represent short-lived (acute) inflammation and infections, persistent (chronic) inflammation, or abnormal growths. Specific disorders include vocal cord polyps and nodules, contact ulcers, ...
Tonsillar Cellulitis and Abscess
Jul 1, 2008
Tonsillar cellulitis is a bacterial infection of the tissues around the tonsils. A tonsillar abscess is a collection of pus behind the tonsils.
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Epiglottitis
Jul 1, 2008
Epiglottitis is a bacterial infection of the epiglottis.
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Laryngitis
Jul 1, 2008
Laryngitis is inflammation of the voice box (larynx).
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Vocal Cord Nodules and Polyps
Jul 1, 2008
Vocal cord nodules and polyps are noncancerous (benign) growths that cause hoarseness and a breathy voice.
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Vocal Cord Contact Ulcers
Jul 1, 2008
Vocal cord contact ulcers are raw sores on the mucous membrane covering the cartilage to which the vocal cords are attached.
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Vocal Cord Paralysis
Jul 1, 2008
Vocal cord paralysis is the inability to move the muscles that control the vocal cords.
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Laryngoceles
Jul 1, 2008
Laryngoceles are outpouchings of the mucous membrane of a part of the voice box (larynx).
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Overview of Nose and Throat Cancers
Jul 1, 2008
Often, cancers of the nose and throat are considered together by doctors because of certain similarities. Among the similarities are the causes. Most people who have cancers of the nose and throat use tobacco, drink alcohol, or both....
Laryngeal Cancer
Jul 1, 2008
Cancer of the voice box (larynx), a common area of cancer within the head and neck, occurs more often in men than in women. It is linked to cigarette smoking and alcohol consumption....
Paranasal Sinus Cancer
Jul 1, 2008
Cancer of the paranasal sinuses occurs mainly in the maxillary and ethmoid sinuses (see ). Although rare in the United States, these cancers are more common in Japan and among the Bantu people of South Africa. Doctors are not sure what causes these c...
Nasopharyngeal Cancer
Jul 1, 2008
Cancer of the nasal passages and upper throat (nasopharynx) may occur in people of any age group. Although rare in North America, cancer of the nasopharynx is one of the most common cancers in Asia. This cancer is also more common among Chinese peopl...
Tonsillar Cancer
Jul 1, 2008
Cancer of the tonsils occurs predominantly in men. It is strongly linked to smoking and alcohol consumption. Recent evidence suggests that human papillomavirus (HPV) is associated with tonsil cancer as well. People who have HPV-related tumors and who...
Cataract
Jul 1, 2008
A cataract is a clouding (opacity) of the lens of the eye that causes a progressive, painless loss of vision.
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Uveitis
Jul 1, 2008
Uveitis is inflammation anywhere in the pigmented inside lining of the eye, known as the uvea or uveal tract.
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Overview of Optic Nerve Disorders
Jul 1, 2008
The small photoreceptors of the retina (the inner surface at the back of the eye) sense light and transmit impulses to the optic nerve. The optic nerve from each eye carries impulses to the brain, where visual information is interpreted. Damage to an...
Papilledema
Jul 1, 2008
Papilledema is a condition in which increased pressure in or around the brain causes the optic nerve to swell where it enters the eye.
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Optic Neuritis
Jul 1, 2008
Optic neuritis is inflammation of the optic nerve anywhere along its course.
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Ischemic Optic Neuropathy
Jul 1, 2008
Ischemic optic neuropathy is damage of the optic nerve caused by a blockage of its blood supply.
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Toxic Amblyopia (Nutritional Amblyopia)
Jul 1, 2008
Toxic amblyopia (nutritional amblyopia) is damage to the optic nerve caused by undernutrition or by exposure to a substance that is harmful to the optic nerve, such as lead, wood alcohol, antifreeze, or certain drugs.
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Overview of Somatoform Disorders
Jun 1, 2008
Somatoform disorders include several mental health disorders. In some, people report physical symptoms or concerns that suggest but are not fully explained by a physical disorder. In one, people are preoccupied with a slight or nonexistent d...
Body Dysmorphic Disorder
Jun 1, 2008
In body dysmorphic disorder, a preoccupation with a nonexistent or slight defect in appearance results in significant distress or impairs functioning.
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Conversion Disorder
Jun 1, 2008
In conversion disorder, physical symptoms that resemble those of a neurologic disorder develop. The symptoms are triggered by mental factors such as conflicts or other stresses.
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Hypochondriasis
Jun 1, 2008
In hypochondriasis, people are preoccupied with the fear of having a serious disease or are preoccupied with the belief that they actually have a disease. These feelings are usually based on a misinterpretation of normal bodily sensations or...
Somatization Disorder
Jun 1, 2008
Somatization disorder is a chronic, severe disorder characterized by many recurring physical symptoms that cannot be fully explained by a physical disorder. These symptoms include some combination of pain and digestive, sexual, and neurologi...
Overview of Mood Disorders
Jun 1, 2008
Mood disorders are mental health disorders involving emotional disturbances consisting of long periods of excessive sadness (depression) or excessive joyousness or elation (mania). Depression and mania represent the two extremes, or poles, o...
Depression
Jun 1, 2008
The disorder depression is a feeling of sadness intense enough to interfere with functioning. It may follow a recent loss or other sad event but is out of proportion to that event and lasts beyond an appropriate length of time.
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Bipolar Disorder(Manic-Depressive Illness)
Jun 1, 2008
In bipolar disorder (formerly called manic-depressive illness), episodes of depression alternate with episodes of mania or a less severe form of mania called hypomania. Mania is characterized by excessive physical activity and feelings of el...
Cyclothymic Disorder
Jun 1, 2008
In cyclothymic disorder, relatively mild and short episodes of elation (hypomania) alternate with mild and short episodes of sadness (depression).
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Definition of Eating Disorders
Jun 1, 2008
Eating disorders are grouped into three categories:...
Anorexia Nervosa
Jun 1, 2008
Anorexia nervosa is characterized by a relentless pursuit of thinness, a distorted body image, an extreme fear of obesity, refusal to maintain a minimally normal body weight, and, in women, the absence of menstrual periods.
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Bulimia Nervosa
Jun 1, 2008
Bulimia nervosa is characterized by the repeated rapid consumption of large amounts of food (bingeing), followed by attempts to rid the body of the excess food consumed (purging).
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Binge Eating Disorder
Jun 1, 2008
Binge eating disorder is characterized by the consumption of large amounts of food with a feeling of loss of control (bingeing). Bingeing is not followed by attempts to rid the body of the excess food consumed (purging).
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Overview of Dissociative Disorders
Jun 1, 2008
Occasionally everyone has minor problems integrating their memories, perceptions, identity, and consciousness. For example, people may drive somewhere and then realize that they do not remember the drive. They may not remember it because they are abs...
Depersonalization Disorder
Jun 1, 2008
Depersonalization disorder involves a persistent or recurring feeling of being detached from one's body or mental processes (depersonalization) and a feeling of being an outside observer of one's life.
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Dissociative Amnesia
Jun 1, 2008
Dissociative amnesia is amnesia caused by trauma or stress, resulting in an inability to recall important personal information.
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Dissociative Fugue
Jun 1, 2008
Dissociative fugue involves one or more episodes of sudden, unexpected, but purposeful travel from home during which people cannot remember some or all of their past life, including who they are (their identity). These episodes are called fu...
Dissociative Identity Disorder
Jun 1, 2008
In dissociative identity disorder, formerly called multiple personality disorder, two or more identities alternate within the same person.
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Introduction
Jun 1, 2008
Schizophrenia and delusional disorder are distinct disorders that may share certain features, such as paranoia, suspiciousness, and unrealistic thinking. However, schizophrenia is associated with psychosis—a loss of contact with reality—and with a de...
Schizophrenia
Jun 1, 2008
Schizophrenia is a mental disorder characterized by loss of contact with reality (psychosis), hallucinations (usually, hearing voices), firmly held false beliefs (delusions), abnormal thinking, a restricted range of emotions (flattened affec...
Delusional Disorder
Jun 1, 2008
Delusional disorder is characterized by one or more false beliefs that persist for at least 1 month.
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Overview of Anemia
Jun 1, 2008
Anemia is a condition in which the number of red blood cells or the amount of hemoglobin (the protein that carries oxygen in them) is low.
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Anemia Due to Excessive Bleeding
Jun 1, 2008
Anemia from excessive bleeding results when loss of red blood cells through bleeding exceeds production of new red blood cells.
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Iron Deficiency Anemia
Jun 1, 2008
Iron deficiency anemia results from low or depleted stores of iron, which is needed to produce red blood cells.
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Vitamin Deficiency Anemia
Jun 1, 2008
Vitamin deficiency anemia results from low or depleted levels of vitamin B12 or folate (folic acid).
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Anemia of Chronic Disease
Jun 1, 2008
In anemia of chronic disease, some chronic disorder slows the production of red blood cells, the result of production of proteins called cytokines that interfere with the production of red blood cells.
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Autoimmune Hemolytic Anemia
Jun 1, 2008
Autoimmune hemolytic anemia is a group of disorders characterized by a malfunction of the immune system that produces autoantibodies, which attack red blood cells as if they were substances foreign to the body.
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Sickle Cell Disease
Jun 1, 2008
Sickle cell disease is an inherited condition characterized by sickle (crescent)-shaped red blood cells and chronic anemia caused by excessive destruction of red blood cells.
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Hemoglobin C, S-C, and E Diseases
Jun 1, 2008
Hemoglobin C, S-C, and E diseases are inherited conditions characterized by abnormally shaped red blood cells and chronic anemia that is caused by excessive destruction of red blood cells.
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Thalassemias
Jun 1, 2008
Thalassemias are a group of inherited disorders resulting from an imbalance in the production of one of the four chains of amino acids that make up hemoglobin (the oxygen-carrying protein found in red blood cells).
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Overview of White Blood Cell Disorders
Jun 1, 2008
White blood cells (leukocytes) are an important part of the body's defense against infectious organisms and foreign substances. To defend the body adequately, a sufficient number of white blood cells must receive a message that an infectious...
Neutropenia
Jun 1, 2008
Neutropenia is an abnormally low number of neutrophils in the blood.
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Neutrophilic Leukocytosis
Jun 1, 2008
Neutrophilic leukocytosis is an abnormally high number of neutrophils in the blood.
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Lymphocytopenia
Jun 1, 2008
Lymphocytopenia is an abnormally low number of lymphocytes in the blood.
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Lymphocytic Leukocytosis
Jun 1, 2008
Lymphocytic leukocytosis is an abnormally high number of lymphocytes in the blood.
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Monocyte Disorders
Jun 1, 2008
Monocytes help other white blood cells remove dead or damaged tissues, destroy cancer cells, and regulate immunity against foreign substances. Monocytes are produced in the bone marrow and then enter the bloodstream, where they account for about 1 to...
Eosinophilic Disorders
Jun 1, 2008
Eosinophils usually account for less than 7% of the circulating leukocytes (100 to 500 eosinophils per microliter of blood). These cells have a role in the protective immunity against certain parasites but also contribute to the inflammation that occ...
Basophilic Disorders
Jun 1, 2008
Basophils account for less than 3% of the circulating leukocytes (0 to 300 basophils per microliter of blood). These cells have some role in immune surveillance and wound repair. Basophils can release histamine and other mediators and play a role in ...
Overview of Leukemia
Jun 1, 2008
Leukemias are cancers of white blood cells or of cells that develop into white blood cells.
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Acute Lymphocytic Leukemia (ALL)
Jun 1, 2008
Acute lymphocytic (lymphoblastic) leukemia is a life-threatening disease in which the cells that normally develop into lymphocytes become cancerous and rapidly replace normal cells in the bone marrow.
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Acute Myelocytic Leukemia (AML)
Jun 1, 2008
Acute myelocytic (myeloid, myelogenous, myeloblastic, myelomonocytic) leukemia is a life-threatening disease in which the cells that normally develop into neutrophils, basophils, eosinophils, and monocytes become cancerous and rapidly replac...
Chronic Lymphocytic Leukemia (CLL)
Jun 1, 2008
Chronic lymphocytic leukemia is a disease in which mature lymphocytes become cancerous and gradually replace normal cells in lymph nodes.
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Chronic Myelocytic Leukemia (CML)
Jun 1, 2008
Chronic myelocytic (myeloid, myelogenous, granulocytic) leukemia is a disease in which cells that normally would develop into neutrophils, basophils, eosinophils, and monocytes become cancerous.
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Overview of the Spleen
Jun 1, 2008
The spleen, a spongy, soft organ about as big as a person's fist, is located in the upper left part of the abdomen, just under the rib cage. The splenic artery brings blood to the spleen from the heart. Blood leaves the spleen through the splenic vei...
Enlarged Spleen
Jun 1, 2008
An enlarged spleen (splenomegaly) is not a disease in itself but the result of an underlying disorder. Many disorders can make the spleen enlarge. To pinpoint the cause, doctors must consider disorders ranging from chronic infections to blood cancers...
Spleen Injury
Jun 1, 2008
Because of the spleen's position in the abdomen, a severe blow to the stomach area can damage the spleen, tearing its covering, the tissue inside, or both. The tears range from small ones that stop bleeding spontaneously to very large ones that cause...
Diabetes Mellitus
Jun 1, 2008
Diabetes mellitus is a disorder in which blood sugar (glucose) levels are abnormally high because the body does not produce enough insulin to meet its needs.
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Multiple Endocrine Neoplasia Syndromes
Jun 1, 2008
Multiple endocrine neoplasia syndromes are rare, inherited conditions in which several endocrine glands develop noncancerous (benign) or cancerous (malignant) tumors or grow excessively without forming tumors.
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Overview of Conjunctival and Scleral Disorders
Jun 1, 2008
The conjunctiva is the thin, transparent lining that covers the back of the eyelid and loops back to cover the sclera (the white of the eye), right up to the edge of the cornea (see ). The conjunctiva helps protect the eye by keeping small foreign ob...
Infectious Conjunctivitis
Jun 1, 2008
Infectious conjunctivitis is inflammation of the conjunctiva usually caused by viruses or bacteria.
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Trachoma
Jun 1, 2008
Trachoma (also called granular conjunctivitis or Egyptian ophthalmia) is a prolonged infection of the conjunctiva caused by the higher bacterium Chlamydia trachomatis.
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Allergic Conjunctivitis
Jun 1, 2008
Allergic conjunctivitis is inflammation of the conjunctiva caused by an allergic reaction.
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Episcleritis
Jun 1, 2008
Episcleritis is inflammation of the tissue lying between the sclera and the conjunctiva.
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Scleritis
Jun 1, 2008
Scleritis is a deep, extremely painful inflammation and purple discoloration of the sclera (the white of the eye) that may severely damage vision.
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Noncancerous Growths
Jun 1, 2008
Two kinds of noncancerous (benign) growths commonly develop on the conjunctiva—pinguecula and pterygium. They both are more common among older people and probably occur as a result of long-term ultraviolet radiation exposure. Doctors easily recognize...
Central Nervous System Infections
May 1, 2008
The central nervous system consists of the brain and spinal cord. These organs are remarkably resistant to infection, but when they become infected, the consequences are often very serious. Infections may be caused by bacteria, viruses, fungi, or, oc...
Rabies
May 1, 2008
Rabies is a viral infection of the brain that is transmitted by animals and that causes inflammation of the brain and spinal cord. Once the virus reaches the spinal cord and brain, rabies is fatal.
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Encephalitis
May 1, 2008
Encephalitis is inflammation of the brain that occurs when a virus directly infects the brain or when a virus or something else triggers inflammation. The spinal cord may also be involved, resulting in a disorder called encephalomyelitis.
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Progressive Multifocal Leukoencephalopathy
May 1, 2008
Progressive multifocal leukoencephalopathy is a rare infection of the brain that is caused by the JC virus.
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Abscess of the Brain
May 1, 2008
A brain abscess is a localized collection of pus in the brain.
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Subdural Empyema
May 1, 2008
A subdural empyema is a collection of pus that develops under the top layer of tissue (dura mater) covering the brain, rather than in the brain itself.
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Parasitic Brain Infections
May 1, 2008
In some parts of the world, brain infections may be due to worms or other parasites. These infections are more common in developing countries and rural areas. They are less common in the United States....
Definition of Meningitis
May 1, 2008
Inflammation that involves the fluid-filled space within the layers of tissue (meninges) that cover the brain and spinal cord are called meningitis. Meningitis is usually caused by bacterial or viral infection. Less often, meningitis results from dis...
Acute Bacterial Meningitis
May 1, 2008
Acute bacterial meningitis is rapidly developing inflammation of the subarachnoid space (located within the layers of tissue covering the brain and spinal cord) that is caused by bacteria.
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Chronic Meningitis
May 1, 2008
Chronic meningitis is a slowly developing inflammation of the subarachnoid space (located within the layers of tissues covering the brain and spinal cord) that lasts a month or longer.
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Aseptic Meningitis
May 1, 2008
Aseptic meningitis is inflammation of the subarachnoid space (located within the layers of tissue covering the brain and spinal cord) that is diagnosed when standard testing does not detect bacteria.
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Lymphocytic Choriomeningitis
May 1, 2008
Lymphocytic choriomeningitis is a flu-like disorder caused by an arenavirus and often followed by meningitis. It occurs when the tissues covering the brain and spinal cord become inflamed.
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Suicidal Behavior
May 1, 2008
Suicidal behavior includes three types of self-destructive acts: completed suicide, attempted suicide, and suicide gestures. Thoughts and plans about suicide are called suicide ideation.
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Carcinoid Tumors
May 1, 2008
Carcinoid tumors are noncancerous (benign) or cancerous (malignant) growths that sometimes produce excessive amounts of hormone-like substances, resulting in the carcinoid syndrome.
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Acute Bronchitis
Apr 1, 2008
Bronchitis is inflammation of the large airways that branch off the trachea (bronchi), usually caused by infection but sometimes caused by irritation from inhaling gases, smoke, dust particles, or some types of pollution.
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Overview of Pneumonia
Apr 1, 2008
Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them.
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Community-Acquired Pneumonia
Apr 1, 2008
Community-acquired pneumonia develops in people with limited or no contact with medical institutions or settings.
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Hospital-Acquired and Institution-Acquired Pneumonia
Apr 1, 2008
Hospital-acquired pneumonia develops in people who have been hospitalized, typically after about 2 days or more of hospitalization. Institution-acquired pneumonia develops in people who reside in nursing homes or who have contact ...
Pneumonia in Immunocompromised People
Apr 1, 2008
Pneumonia in people whose immune system is weakened (for example, by AIDS, organ transplantation, or the use of certain drugs) is usually caused by different organisms than those that cause pneumonia in healthy people.
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Aspiration Pneumonia
Apr 1, 2008
Aspiration pneumonia is lung infection caused by inhaling mouth secretions, stomach contents, or both. Chemical pneumonitis is lung irritation caused by inhalation of substances toxic to the lungs.
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Asthma
Apr 1, 2008
Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli.
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Overview of Environmental Lung Diseases
Apr 1, 2008
Environmental lung diseases are caused by harmful particles, mists, vapors, or gases that are inhaled, usually while people work. If the lung disease is due to inhaled particles, the term pneumoconiosis is often used. Where within the airways or lung...
Asbestosis
Apr 1, 2008
Asbestosis is widespread scarring of lung tissue caused by breathing asbestos dust.
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Beryllium Disease
Apr 1, 2008
Beryllium disease (sometimes called berylliosis) is a lung inflammation caused by inhaling dust or fumes that contain beryllium.
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Building-Related Illnesses
Apr 1, 2008
Building-related illnesses are disorders that affect the lungs as well as other parts of the body and are caused by exposure to substances within modern airtight buildings.
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Byssinosis
Apr 1, 2008
Byssinosis is a narrowing of the airways caused by inhaling cotton, flax, or hemp particles.
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Coal Workers' Pneumoconiosis
Apr 1, 2008
Coal workers' pneumoconiosis (black lung) is a lung disease caused by deposits of coal dust in the lungs.
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Gas and Chemical Exposure
Apr 1, 2008
Many types of gases—such as chlorine, phosgene, sulfur dioxide, hydrogen sulfide, nitrogen dioxide, and ammonia—may suddenly be released during industrial accidents and may severely irritate the lungs. Gases such as chlorine and ammonia easily dissol...
Occupational Asthma
Apr 1, 2008
Occupational asthma is a reversible narrowing of the airways caused by inhaling work-related particles or vapors that act as irritants or cause an allergic reaction.
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Silicosis
Apr 1, 2008
Silicosis is permanent scarring of the lungs caused by inhaling silica (quartz) dust.
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Bone Tumors
Apr 1, 2008
Bone tumors are growths of abnormal cells in bones.
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Other Bone Abnormalities
Apr 1, 2008
Many noncancerous (benign) bone abnormalities may resemble bone tumors but are not....
Joint Tumors
Apr 1, 2008
Tumors rarely affect joints unless the joints are near a bone or soft-tissue tumor. However, two conditions—synovial chondromatosis and pigmented villonodular synovitis—occur in the lining (synovium) of joints. These tumors are noncancerous (benign) ...
Overview of Vasculitis
Apr 1, 2008
Vasculitic disorders are characterized by inflammation of the blood vessels (vasculitis).
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Polyarteritis Nodosa
Apr 1, 2008
Polyarteritis nodosa is inflammation of medium-sized arteries that damages the arteries and impairs blood flow through them.
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Giant Cell Arteritis
Apr 1, 2008
Giant cell (temporal) arteritis is chronic inflammation of large arteries of the head, neck, and upper body. Typically affected are the temporal arteries, which run through the temples and provide blood to part of the scalp, the jaw muscles,...
Wegener's Granulomatosis
Apr 1, 2008
Wegener's granulomatosis often begins with inflammation of small and medium-sized blood vessels and tissues in the nose, sinuses, throat, or lungs. It may progress to inflammation of blood vessels throughout the body (generalized vasculitis)...
Behçet's Syndrome
Apr 1, 2008
Behçet's syndrome is chronic inflammation that can cause painful mouth sores, skin blisters, genital sores, and swollen joints. The eyes, blood vessels, nervous system, and digestive tract may also become inflamed.
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Takayasu's Arteritis
Apr 1, 2008
Takayasu's arteritis causes chronic inflammation, mainly of the aorta (the artery that connects directly with the heart), the arteries that branch off from it, and the pulmonary arteries.
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Churg-Strauss Syndrome
Apr 1, 2008
Churg-Strauss syndrome is inflammation of small blood vessels that damages organs and that usually occurs in people with a history of asthma, nasal allergies, or both.
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Henoch-Schönlein Purpura
Apr 1, 2008
Henoch-Schönlein purpura is inflammation mainly of small vessels, usually occurring in children.
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Microscopic Polyangiitis
Apr 1, 2008
Microscopic polyangiitis is inflammation of mainly small vessels throughout the body.
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Low Back Pain
Apr 1, 2008
Low back pain is very common and becomes more common as people age. It is very costly in terms of healthcare payments, disability payments, and missed work. Thus, although low back pain rarely results from life-threatening disorders, it is a signific...
Neck Pain
Apr 1, 2008
The neck's flexibility makes it susceptible to wear and tear and to injuries that overstretch it, such as whiplash. Also, the neck has the critical job of holding up the head. Poor posture makes that job more difficult. Thus, neck pain, like back pai...
Muscle Cramps
Apr 1, 2008
A cramp is a sudden, brief, usually painful contraction of a muscle or group of muscles.
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Fibromyalgia
Apr 1, 2008
Fibromyalgia is characterized by poor sleep, fatigue, and widespread aching and stiffness in soft tissues, including muscles, tendons, and ligaments.
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Bursitis
Apr 1, 2008
Bursitis is painful inflammation of a bursa (a flat, fluid-filled sac that provides cushioning where skin, muscles, tendons, and ligaments rub over bones).
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Tendinitis and Tenosynovitis
Apr 1, 2008
Tendinitis is inflammation of a tendon. Tenosynovitis is tendinitis accompanied by inflammation of the protective covering around the tendon (tendon sheath).
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Baker's Cysts
Apr 1, 2008
Baker's cysts (popliteal cysts) are tiny sacs filled with joint (synovial) fluid that form in an extension of the joint capsule behind the knee.
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Amyloidosis
Apr 1, 2008
Amyloidosis is a rare disease in which a protein called amyloid accumulates in various tissues and organs, impairing normal function.
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Overview of Imaging Tests
Apr 1, 2008
Imaging tests provide a picture of the body's interior—of the whole body or part of it. Most imaging tests are painless, relatively safe, and noninvasive (that is, they do not require an incision in the skin or the insertion of an instrument into the...
Angiography
Apr 1, 2008
In angiography, x-rays are used to produce detailed images of blood vessels. It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography and magnetic resonance angiography. During angiography, doctors c...
Computed Tomography
Apr 1, 2008
In computed tomography (CT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually has 4 to 64 or more rows of sensors that record the x-rays that pass through the body. Data from the sensors repres...
Magnetic Resonance Imaging
Apr 1, 2008
In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe....
Plain X-Rays
Apr 1, 2008
X-rays are high-energy radiation waves that can penetrate most substances (to varying degrees). In low doses, x-rays are used to produce images that help doctors diagnose disease. In high doses, x-rays (radiation therapy) is used to treat cancer. X-r...
Radionuclide Scanning
Apr 1, 2008
In radionuclide scanning, radionuclides are used to produce images. A radionuclide is an unstable atom that becomes more stable by releasing energy as radiation. Most radionuclides release high-energy photons as gamma rays (which are similar to x-ray...
Ultrasonography
Apr 1, 2008
Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves, which are sent into the body's tissues. Sound waves bounce...
Overview of Interstitial Lung Diseases
Mar 1, 2008
Interstitial lung disease (also called diffuse parenchymal or infiltrative lung disease) is a term used to describe a number of different disorders that affect the interstitial space. The interstitial space consists of the air sacs of the lungs (alve...
Idiopathic Interstitial Pneumonias
Mar 1, 2008
Idiopathic interstitial pneumonias are interstitial lung diseases that have no known cause and that affect the lungs similarly.
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Pulmonary Langerhans' Cell Granulomatosis
Mar 1, 2008
Pulmonary Langerhans' cell granulomatosis (histiocytosis or eosinophilic granuloma) is a disorder in which cells called histiocytes and eosinophils proliferate in the lung, often causing scarring.
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Lymphoid Interstitial Pneumonia
Mar 1, 2008
Lymphoid interstitial pneumonia is an uncommon lung disease in which mature lymphocytes (a type of white blood cell) accumulate in the alveoli.
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Sarcoidosis
Mar 1, 2008
Sarcoidosis is a disease in which abnormal collections of inflammatory cells (granulomas) form in many organs of the body.
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Pulmonary Alveolar Proteinosis
Mar 1, 2008
Pulmonary alveolar proteinosis is a rare disorder in which the air sacs of the lungs (alveoli) become plugged with a protein-rich fluid.
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Pulmonary Hypertension
Mar 1, 2008
Pulmonary hypertension is a condition in which blood pressure in the arteries of the lungs (the pulmonary arteries) is abnormally high.
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Lung Cancer
Mar 1, 2008
Lung cancer is the leading cause of cancer death in both men and women. It occurs most commonly between the ages of 45 and 70 and has become more prevalent in women in the last few decades because more women are smoking cigarettes....
Osteonecrosis
Mar 1, 2008
Osteonecrosis, also referred to as avascular necrosis of bone, aseptic necrosis, ischemic necrosis, or osteochondritis dissecans, is the death of a segment of bone caused by an impaired blood supply.
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Ganglia
Mar 1, 2008
Ganglia (ganglion cysts) are gelatinous swellings on the hands and wrists.
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Hand and Finger Deformities
Mar 1, 2008
Hand deformities may be caused by an injury or may result from another disorder (for example, rheumatoid arthritis—see ). Deformities should be treated promptly, if possible. Otherwise, they tend not to respond to simple treatments, such as splinting...
Nerve Compression Syndromes
Mar 1, 2008
Carpal tunnel syndrome, cubital tunnel syndrome, and radial tunnel syndrome are nerve compression syndromes. In these disorders, something (usually bone or connective tissue) presses on a nerve, causing abnormalities of sensation, movement, or both. ...
Kienböck's Disease
Mar 1, 2008
Kienböck's disease is the death of bone tissue due to an impaired blood supply (avascular necrosis—see ) affecting the lunate bone in the hand.
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Hand Injuries
Mar 1, 2008
Hand injuries cause swelling, pain, stiffness, and sometimes limited movement. The most common injuries are tears (ruptures) of ligaments or fractures of bone. When a ligament is ruptured, bones can move out of position, resulting in a dislocated joi...
Hand and Finger Infections
Mar 1, 2008
Human and animal bites can cause an infection of the hands. Some other infections are felon and herpetic whitlow. Paronychia is discussed elsewhere (see )....
Overview of Foot Problems
Mar 1, 2008
Some foot problems start in the foot itself, for example, from a foot injury. Others result from disorders that affect many parts of the body, such as diabetes, gout, or other types of arthritis. Problems can occur in any bone, joint, muscle, tendon,...
Pain in the Ball of the Foot (Metatarsalgia)
Mar 1, 2008
Pain in the ball of the foot (called metatarsalgia) may have many different causes (including arthritis, poor circulation, pinching of the nerves between the toes, posture problems, and various disorders). However, most often the pain is caused by ne...
Tarsal Tunnel Syndrome
Mar 1, 2008
Tarsal tunnel syndrome (posterior tibial neuralgia) is pain in the ankle, foot, and toes caused by compression of or damage to the nerve supplying the heel and sole (posterior tibial nerve).
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Medial Plantar Nerve Entrapment
Mar 1, 2008
Medial plantar nerve entrapment is compression of a nerve at the inner heel (the medial plantar nerve) that causes pain, numbness, or tingling.
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Tibialis Posterior Tendinosis
Mar 1, 2008
Tibialis posterior tendinosis is wear and tear of a tendon that passes behind and around the inner ankle.
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Plantar Fasciosis
Mar 1, 2008
Plantar fasciosis is pain originating from the dense band of tissue called the plantar fascia that extends from the bottom of the heel bone to the base of the toes (ball of the foot).
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Inferior Calcaneal Bursitis
Mar 1, 2008
Bursitis is painful inflammation of a bursa (a flat sac containing joint [synovial] fluid that reduces friction in areas where skin, muscles, tendons, and ligaments rub over bones). Bursitis can develop at the bottom of the heel. The heel may throb, ...
Achilles Tendon Bursitis
Mar 1, 2008
Achilles tendon bursitis is inflammation of the fluid-filled sac (bursa) located either between the skin of the heel and the Achilles tendon (posterior Achilles tendon bursitis) or in front of the attachment of the Achilles tendon to the hee...
Achilles Tendon Enthesopathy
Mar 1, 2008
Achilles tendon enthesopathy is pain where the Achilles tendon attaches to the back of the heel.
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Corns and Calluses
Mar 1, 2008
Corns are hard cone-shaped bumps of skin commonly found on the upper surface of the smaller toes, particularly over a joint. Calluses are somewhat rounded flat thickenings of the skin located on the under-surface of the foot.
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Bunion
Mar 1, 2008
In bunion, the joint of the base of the big toe appears to stick out (becomes prominent).
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Hammer Toe
Mar 1, 2008
Hammer toe is a toe that is in a fixed (rigid) contracted position.
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Plantar Fibromatosis
Mar 1, 2008
Plantar fibromatosis is a noncancerous (benign) growth of connective tissue in the sole (the plantar fascia).
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Overview of Sleep and Sleep Disorders
Mar 1, 2008
Sleep disorders are disturbances that affect the ability to fall asleep, stay asleep, or stay awake or that cause abnormal behaviors during sleep, such as night terrors or sleepwalking.
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Snoring
Mar 1, 2008
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Insomnia
Mar 1, 2008
Insomnia is difficulty falling asleep or staying asleep or a disturbance in sleep quality that makes sleep seem inadequate or unrefreshing.
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Circadian Rhythm Sleep Disorders
Mar 1, 2008
Circadian rhythm sleep disorders occur when people's internal sleep-wake schedule (clock) does not align with the earth's cycle of darkness (night) and light (day).
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Hypersomnia and Excessive Daytime Sleepiness
Mar 1, 2008
Hypersomnia is a substantial increase in total sleeping time. Excessive daytime sleepiness (EDS) is the inability to stay awake and alert during the day, resulting in unintended lapses into drowsiness or sleep.
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Narcolepsy
Mar 1, 2008
Narcolepsy is a sleep disorder marked by excessive sleepiness during the day or recurring, uncontrollable episodes of sleep during normal waking hours, plus sudden episodes of muscle weakness (cataplexy). Sometimes sleep paralysis, vivid dre...
Periodic Limb Movement Disorder and Restless Legs Syndrome
Mar 1, 2008
Periodic limb movement disorder involves repetitive movements of the arms, legs, or both during sleep. Restless legs syndrome involves an irresistible urge to move and usually abnormal sensations in the legs, arms, or both when people sit st...
Parasomnias
Mar 1, 2008
Parasomnias are unusual behaviors that occur during sleep.
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Sleep Disorders in Dementia
Mar 1, 2008
In people with dementia (see ), such as Alzheimer's disease, sleep patterns are often abnormal. As dementia progresses, the time spent in light sleep increases, so people are easily awakened.People with dementia may have disorders that contribute to ...
Overview of Brain Dysfunction
Mar 1, 2008
Brain damage can cause many types of dysfunction. Such dysfunction ranges from complete loss of consciousness (as occurs in a coma), to disorientation and an inability to pay attention (as occurs in delirium), to impairment of one or several of the m...
Brain Dysfunction by Location
Mar 1, 2008
Because different areas of the brain control specific functions (see also ), the location of brain damage determines the type of dysfunction that results. Which side of the brain is affected is also important because the functions of the two halves o...
Specific Types of Brain Dysfunction
Mar 1, 2008
Many functions of the brain are performed by several areas of the brain working together (networks), not by a single area in the brain. Damage to these networks can cause aphasia, apraxia, agnosia, or amnesia....
Seizure Disorders
Mar 1, 2008
In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction.
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Overview of Demyelinating Disorders
Mar 1, 2008
Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath. Much like the insulation around an electrical wire, the myelin sheath enables el...
Multiple Sclerosis (MS)
Mar 1, 2008
In multiple sclerosis, patches of myelin and underlying nerve fibers in the eyes, brain, and spinal cord are damaged or destroyed.
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Other Primary Demyelinating Diseases
Mar 1, 2008
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Overview of Cornary Artery Disease
Feb 1, 2008
Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked.
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Angina
Feb 1, 2008
Angina, also called angina pectoris, is temporary chest pain or a sensation of pressure that occurs while the heart muscle is not receiving enough oxygen.
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Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina)
Feb 1, 2008
Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or heart attack (myocardial infarction) depending on the location and amount of blockage.
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Overview of the Venous System
Feb 1, 2008
Veins return blood to the heart from all the organs of the body. The large veins parallel the large arteries and often share the same name, but the pathways of the venous system are more difficult to trace than those of the arteries. Many unnamed sma...
Deep Vein Thrombosis (DVT)
Feb 1, 2008
Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins.
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Superficial Thrombophlebitis
Feb 1, 2008
Superficial thrombophlebitis (superficial phlebitis) is inflammation and clotting in a superficial vein.
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Varicose Veins
Feb 1, 2008
Varicose veins are abnormally enlarged superficial veins in the legs.
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Arteriovenous Fistula
Feb 1, 2008
An arteriovenous fistula is an abnormal channel between an artery and a vein.
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Overview of the Lymphatic System
Feb 1, 2008
Like the venous system, the lymphatic system transports fluids throughout the body. The lymphatic system consists of thin-walled lymphatic vessels, lymph nodes, and two collecting ducts (see ). Lymphatic vessels, located throughout the body, are larg...
Lymphedema
Feb 1, 2008
Lymphedema is the accumulation of lymph resulting in swelling.
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Bronchiectasis
Feb 1, 2008
Bronchiectasis is an irreversible widening (dilation) of portions of the breathing tubes or airways (bronchi) resulting from damage to the airway wall.
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Atelectasis
Feb 1, 2008
Atelectasis is a condition in which all or part of a lung becomes airless and collapses.
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Overview of Pleural Disorders
Feb 1, 2008
The pleura is a thin, transparent, two-layered membrane that covers the lungs and also lines the inside of the chest wall. The layer that covers the lungs lies in close contact with the layer that lines the chest wall. Between the two thin flexible l...
Pleural Effusion
Feb 1, 2008
Pleural effusion is the abnormal accumulation of fluid in the pleural space.
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Pneumothorax
Feb 1, 2008
A pneumothorax is the presence of air between the two layers of pleura, resulting in partial or complete collapse of the lung.
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Viral Pleuritis
Feb 1, 2008
Viral pleuritis is a viral infection of the pleurae, which typically causes chest pain when breathing or coughing.
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Osteoporosis
Feb 1, 2008
Osteoporosis is a condition in which a progressive decrease in the density of bones weakens the bones, making fractures likely.
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Osteomyelitis
Feb 1, 2008
Osteomyelitis is a bone infection usually caused by bacteria, including mycobacteria, but is sometimes caused by fungi.
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Infectious Arthritis
Feb 1, 2008
Infectious arthritis (septic arthritis) is infection in the fluid and tissues of a joint usually caused by bacteria, but sometimes caused by viruses or fungi.
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Osteoarthritis (OA)
Feb 1, 2008
Osteoarthritis (sometimes called degenerative arthritis, degenerative joint disease, osteoarthrosis, or hypertrophic osteoarthritis) is a chronic disorder associated with damage to the cartilage and surrounding tissues and characterized by p...
Rheumatoid Arthritis (RA)
Feb 1, 2008
Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.
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Other Types of Inflammatory Arthritis
Feb 1, 2008
Several connective tissue diseases, including the spondyloarthropathies (also called spondyloarthritides), cause prominent joint inflammation. The spondyloarthropathies affect the joints and spine. These disorders share certain characteristics. For e...
Charcot's Joints
Feb 1, 2008
Charcot's joints (neurogenic arthropathy, neuropathic arthropathy) is progressive joint destruction, often very rapid, that develops because people cannot sense pain and thus are not aware of the early signs of joint damage.
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Overview of Autoimmune Disorders of Connective Tissue
Feb 1, 2008
In an autoimmune disorder, antibodies or cells produced by the body attack the body's own tissues (see ). Many autoimmune disorders affect connective tissue in a variety of organs. Connective tissue is the structural tissue that gives strength to joi...
Systemic Lupus Erythematosus (SLE)
Feb 1, 2008
Systemic lupus erythematosus (disseminated lupus erythematosus or lupus) is a chronic inflammatory connective tissue disorder that can involve joints, kidneys, mucous membranes, and blood vessel walls.
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Systemic Sclerosis (Scleroderma)
Feb 1, 2008
Systemic sclerosis (scleroderma) is a rare, chronic disorder characterized by degenerative changes and scarring in the skin, joints, and internal organs and by blood vessel abnormalities.
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Sjögren's Syndrome
Feb 1, 2008
Sjögren's syndrome is characterized by excessive dryness of the eyes, mouth, and other mucous membranes.
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Polymyositis and Dermatomyositis
Feb 1, 2008
Polymyositis is characterized by inflammation and degeneration of the muscles. Dermatomyositis is polymyositis accompanied by skin inflammation.
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Mixed Connective Tissue Disease (MCTD)
Feb 1, 2008
Mixed connective tissue disease is a term used by some doctors to describe a disorder characterized by features of systemic lupus erythematosus, systemic sclerosis, and polymyositis.
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Relapsing Polychondritis
Feb 1, 2008
Relapsing polychondritis is characterized by episodes of painful, destructive inflammation of the cartilage and other connective tissues in many organs.
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Eosinophilic Fasciitis
Feb 1, 2008
Eosinophilic fasciitis is a rare disorder in which the skin of the arms and legs becomes painfully inflamed and swollen and gradually hardens.
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Gout
Feb 1, 2008
Gout is a disorder that results from deposits of sodium uric acid crystals, which accumulate in the joints because of high blood levels of uric acid (hyperuricemia), leading to attacks of painful joint inflammation.
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Pseudogout
Feb 1, 2008
Pseudogout (calcium pyrophosphate dihydrate crystal deposition disease) is a disorder caused by deposits of calcium pyrophosphate dihydrate crystals in the cartilage and then in the fluid of the joints, leading to intermittent attacks of pai...
Overview of Delirium and Dementia
Feb 1, 2008
Delirium and dementia are the most common causes of mental (cognitive) dysfunction—the inability to acquire, retain, and use knowledge normally. Although delirium and dementia may occur together, they are quite different. Delirium b...
Delirium
Feb 1, 2008
Delirium is a sudden, fluctuating, and usually reversible disturbance of mental function. It is characterized by inability to pay attention, disorientation, an inability to think clearly, and fluctuations in the level of alertness (conscious...
Dementia
Feb 1, 2008
Dementia is a slow, progressive decline in mental function including memory, thinking, judgment, and the ability to learn.
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Stupor and Coma
Feb 1, 2008
Stupor is unresponsiveness from which a person can be aroused only by vigorous, physical stimulation. Coma is unresponsiveness from which a person cannot be aroused. In coma, the person's eyes remain closed.
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Introduction
Feb 1, 2008
A tumor is an abnormal growth, whether noncancerous (benign) or cancerous (malignant). In many parts of the body, a noncancerous tumor causes few or no problems. However, any abnormal growth or mass in the brain or spinal cord can cause considerable ...
Brain Tumors
Feb 1, 2008
A brain tumor is a noncancerous (benign) or cancerous (malignant) growth in the brain. It may originate in the brain or have spread (metastasized) to the brain from another part of the body.
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Spinal Cord Tumors
Feb 1, 2008
A spinal cord tumor is a noncancerous (benign) or cancerous (malignant) growth in or around the spinal cord.
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Radiation Damage
Feb 1, 2008
Radiation therapy is one component in the treatment of tumors of the nervous system. It is directed at the general area (such as the whole head) when people have several tumors or a tumor that does not have distinct borders. When the tumor has distin...
Overview of the Peripheral Nervous System
Feb 1, 2008
The peripheral nervous system refers to the parts of nervous system outside the central nervous system, that is, those outside the brain and spinal cord. The nerves that connect the head, face, eyes, nose, muscles, and ears to the brain (cranial nerv...
Muscle Stimulation Disorders
Feb 1, 2008
Muscle stimulation (motor neuron) disorders are characterized by progressive deterioration of the nerves and other structures involved in muscle movement. These disorders develop when motor nerves do not stimulate muscles normally.
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Neuromuscular Junction Disorders
Feb 1, 2008
Nerves connect with muscles at the neuromuscular junction. There, the ends of nerve fibers connect to special sites on the muscle's membrane called motor end plates. These plates contain receptors that enable the muscle to respond to acetylcholine, a...
Myasthenia Gravis
Feb 1, 2008
Myasthenia gravis is an autoimmune disorder that impairs communication between nerves and muscles, resulting in episodes of muscle weakness.
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Botulism
Feb 1, 2008
Botulism is an uncommon, life-threatening poisoning caused by toxins produced by the bacterium Clostridium botulinum.
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Eaton-Lambert Syndrome
Feb 1, 2008
Eaton-Lambert syndrome is an autoimmune disorder that causes weakness.
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Plexus Disorders
Feb 1, 2008
The networks of interwoven nerve fibers from different spinal nerves (plexuses) may be damaged by injury, tumors, collections of blood, or autoimmune reactions.
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Thoracic Outlet Syndromes
Feb 1, 2008
Thoracic outlet syndromes are a group of disorders caused by pressure on nerves as they pass between the neck and chest. These disorders cause pain and pins-and-needles sensations (paresthesias) in the hand, shoulder, and arm.
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Mononeuropathy
Feb 1, 2008
Mononeuropathy is damage to a single peripheral nerve.
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Multiple Mononeuropathy
Feb 1, 2008
Multiple mononeuropathy (mononeuritis multiplex) is the simultaneous malfunction of two or more peripheral nerves in separate areas of the body. It causes abnormal sensations and weakness.
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Polyneuropathy
Feb 1, 2008
Polyneuropathy is the simultaneous malfunction of many peripheral nerves throughout the body.
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Hereditary Neuropathies
Feb 1, 2008
Hereditary neuropathies affect the peripheral nerves, causing subtle symptoms that worsen gradually.
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Spinal Muscular Atrophies
Feb 1, 2008
Spinal muscular atrophies are hereditary disorders in which nerve cells in the spinal cord and brain stem degenerate, causing progressive muscle weakness and wasting.
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Overview of the Middle and Inner Ear
Feb 1, 2008
The middle ear consists of the eardrum (tympanic membrane) and an air-filled chamber containing a chain of three bones (ossicles) that connect the eardrum to the inner ear (see ). The fluid-filled inner ear (labyrinth) consists of two major parts: th...
Eardrum Perforation
Feb 1, 2008
A perforation is a hole in the eardrum.
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Barotrauma of the Ear
Feb 1, 2008
Barotrauma (barotitis media or aerotitis media) is damage to the middle ear caused by unequal air pressure on the two sides of the eardrum.
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Infectious Myringitis
Feb 1, 2008
Infectious myringitis is infection of the eardrum by a virus or bacteria.
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Otitis Media (Acute)
Feb 1, 2008
Acute otitis media is a bacterial or viral infection of the middle ear.
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Otitis Media (Secretory)
Feb 1, 2008
Secretory otitis media is an accumulation of fluid in the middle ear.
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Otitis Media (Chronic)
Feb 1, 2008
Chronic otitis media is a long-standing infection of the middle ear.
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Mastoiditis
Feb 1, 2008
Mastoiditis is a bacterial infection in the mastoid process, the prominent bone behind the ear.
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Meniere's Disease
Feb 1, 2008
Meniere's disease is a disorder characterized by recurring attacks of disabling vertigo (a whirling sensation), hearing loss, and noise in the ear (tinnitus).
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Vestibular Neuronitis
Feb 1, 2008
Vestibular neuronitis is a disorder characterized by a sudden severe attack of vertigo (a whirling sensation), caused by inflammation of the nerve to the semicircular canals.
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Temporal Bone Fracture
Feb 1, 2008
The temporal bone (the skull bone containing part of the ear canal, the middle ear, and the inner ear) can be fractured by a blow to the head.
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Auditory Nerve Tumors
Feb 1, 2008
An auditory nerve tumor (acoustic neuroma, acoustic neurinoma, vestibular schwannoma, eighth nerve tumor) is a noncancerous (benign) tumor that originates in the cells that wrap around the auditory nerve (Schwann cells).
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Tinnitus
Feb 1, 2008
Tinnitus is noise originating in the ear rather than in the environment.
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Overview of Bone Disorders in Children
Feb 1, 2008
Children's bones grow continually and reshape (remodel) themselves extensively. Growth proceeds from a vulnerable part of the bone called the growth plate. In remodeling, old bone tissue is gradually replaced by new bone tissue (see ). Many bone diso...
Scoliosis
Feb 1, 2008
Scoliosis is abnormal curvature of the spine.
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Kyphosis
Feb 1, 2008
Kyphosis (Scheuermann's disease) is an abnormal curving of the spine that causes a humpback.
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Slipped Capital Femoral Epiphysis (SCFE)
Feb 1, 2008
Slipped capital femoral epiphysis is a separation within the thighbone (femur) at its growth plate in the hip joint.
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Legg-Calvé-Perthes Disease
Feb 1, 2008
Legg-Calvé-Perthes disease is destruction of the growth plate of the thighbone.
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Osgood-Schlatter Disease
Feb 1, 2008
Osgood-Schlatter disease is inflammation of the bone and cartilage at the top of the shinbone (tibia).
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Köhler's Bone Disease
Feb 1, 2008
Köhler's bone disease is inflammation of the tarsal navicular bone (a bone at the arch of the foot).
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Sever's Disease
Feb 1, 2008
Sever's disease is inflammation of the heel bone (calcaneus).
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Chondromalacia Patellae
Feb 1, 2008
Chondromalacia patellae (patellofemoral syndrome) is softening of the cartilage under the kneecap (patella).
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Osteopetroses
Feb 1, 2008
Osteopetroses are a group of rare disorders that increase the density of bones.
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Overview of Hereditary Connective Tissue Disorders
Feb 1, 2008
Muscles, bones, cartilage, ligaments, and tendons are built mostly of connective tissue. Connective tissue is also found in other parts of the body, such as the skin and internal organs. Connective tissue is strong and thus able to support weight and...
Cutis Laxa
Feb 1, 2008
Cutis laxa is a rare disorder of connective tissue that causes the skin to stretch easily and hang in loose folds.
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Ehlers-Danlos Syndrome
Feb 1, 2008
Ehlers-Danlos syndrome is a rare disorder of connective tissue that results in unusually flexible joints, very elastic skin, and fragile tissues.
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Marfan Syndrome
Feb 1, 2008
Marfan syndrome is a rare disorder of connective tissue, resulting in abnormalities of the eyes, bones, heart, blood vessels, and central nervous system.
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Osteochondrodysplasias
Feb 1, 2008
Osteochondrodysplasias are a group of rare disorders of bone or cartilage that cause the skeleton to develop abnormally.
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Osteogenesis Imperfecta
Feb 1, 2008
Osteogenesis imperfecta is a group of disorders of bone formation that make the bones abnormally fragile.
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Pseudoxanthoma Elasticum
Feb 1, 2008
Pseudoxanthoma elasticum is a disorder of connective tissue that causes abnormalities in the skin, eyes, and blood vessels.
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Nail-Patella Syndrome
Feb 1, 2008
Nail-patella syndrome (also called osteo-onychodysplasia, arthro-onychodysplasia, and onycho-osteodysplasia) is a rare hereditary disorder that results in abnormalities of the kidneys, bones, joints, and fingernails.
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Heart Failure
Jan 1, 2008
Heart failure is a disorder in which the heart pumps blood inadequately, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and other changes that may further weaken the heart.
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Overview of Cardiomyopathy
Jan 1, 2008
Cardiomyopathy refers to progressive impairment of the structure and function of the muscular walls of the heart chambers.
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Dilated Cardiomyopathy
Jan 1, 2008
Dilated (congestive) cardiomyopathy is a group of heart muscle disorders in which the ventricles enlarge but are not able to pump enough blood for the body's needs, resulting in heart failure.
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Hypertrophic Cardiomyopathy
Jan 1, 2008
Hypertrophic cardiomyopathy includes a group of heart disorders in which the walls of the ventricles thicken (hypertrophy) and become stiff, even though the workload of the heart is not increased.
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Restrictive Cardiomyopathy
Jan 1, 2008
Restrictive (infiltrative) cardiomyopathy includes a group of heart disorders in which the walls of the ventricles become stiff, but not necessarily thickened, and resist normal filling with blood between heartbeats.
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Overview of Abnormal Heart Rhythms
Jan 1, 2008
Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart.
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Atrial Premature Beats
Jan 1, 2008
An atrial premature beat (atrial ectopic beat, premature atrial contraction) is an extra heartbeat caused by electrical activation of the atria from an abnormal site before a normal heartbeat would occur.
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Atrial Fibrillation and Atrial Flutter
Jan 1, 2008
Atrial fibrillation and atrial flutter are very fast electrical discharge patterns that make the atria contract very rapidly, with some of the electrical impulses reaching the ventricles and causing them to contract faster and less efficient...
Paroxysmal Supraventricular Tachycardia (SVT, PSVT)
Jan 1, 2008
Paroxysmal supraventricular (atrial) tachycardia is a regular, fast (160 to 220 beats per minute) heart rate that begins and ends suddenly and originates in heart tissue other than that in the ventricles.
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Wolff-Parkinson-White (WPW) Syndrome
Jan 1, 2008
Wolff-Parkinson-White syndrome is a disorder in which an extra electrical connection between the atria and the ventricles is present at birth. People may have episodes of a very rapid heartbeat.
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Ventricular Premature Beats
Jan 1, 2008
A ventricular premature beat (ventricular ectopic beat, premature ventricular contraction) is an extra heartbeat resulting from abnormal electrical activation originating in the ventricles before a normal heartbeat would occur.
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Ventricular Tachycardia
Jan 1, 2008
Ventricular tachycardia is a heart rhythm that originates in the ventricles and produces a heart rate of at least 120 beats per minute.
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Ventricular Fibrillation
Jan 1, 2008
Ventricular fibrillation is a potentially fatal, uncoordinated series of very rapid, ineffective contractions of the ventricles caused by many chaotic electrical impulses.
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Pacemaker Dysfunction
Jan 1, 2008
Dysfunction of the heart's pacemaker (sinus or sinoatrial node) may result in a persistently slow heartbeat (sinus bradycardia) or complete cessation of normal pacemaker activity (sinus arrest). When activity ceases, another area of the heart usually...
Heart Block
Jan 1, 2008
Heart block is a delay in the conduction of electrical current as it passes through the atrioventricular node, bundle of His, or both bundle branches, all of which are located between the atria and the ventricles.
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Bundle Branch Block
Jan 1, 2008
Bundle branch block is a type of conduction block involving partial or complete interruption of the flow of electrical impulses through the right or left bundle branches.
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Atherosclerosis
Jan 1, 2008
Atherosclerosis is a condition in which patchy deposits of fatty material (atheromas or atherosclerotic plaques) develop in the walls of medium-sized and large arteries, leading to reduced or blocked blood flow.
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Overview of Peripheral Arterial Disease
Jan 1, 2008
Peripheral arterial disease results in reduced blood flow in the arteries of the trunk, arms, and legs.
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Occlusive Peripheral Arterial Disease
Jan 1, 2008
Occlusive peripheral arterial disease is common among older people because it often results from atherosclerosis, which becomes more common with aging. Occlusive peripheral arterial disease may affect 15 to 20% of people older than 70. The disease is...
Functional Peripheral Arterial Disease
Jan 1, 2008
Functional peripheral arterial disease is much less common than occlusive peripheral arterial disease. Normally, the arteries of the arms and legs widen (dilate) and narrow (constrict) in response to changes in the environment, such as a change in te...
Introduction
Jan 1, 2008
The aorta, which is about 1 inch (2.5 centimeters) in diameter, is the largest artery of the body. It receives oxygen-rich blood from the left ventricle and distributes it to all of the body except the lungs (which receive blood from the right ventri...
Aneurysms
Jan 1, 2008
An aneurysm is a bulge (dilation) in the wall of an artery, usually the aorta.
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Aortic Dissection
Jan 1, 2008
An aortic dissection (dissecting aneurysm, dissecting hematoma) is an often fatal disorder in which the inner layer (lining) of the aortic wall tears.
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Abscess in the Lungs
Jan 1, 2008
A lung abscess is a pus-filled cavity in the lung surrounded by inflamed tissue and caused by an infection.
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Respiratory Failure
Jan 1, 2008
Respiratory failure (lung failure) is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide becomes dangerously high.
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Acute Respiratory Distress Syndrome (ARDS)
Jan 1, 2008
Acute respiratory distress syndrome is a type of respiratory (lung) failure resulting from many different disorders that cause fluid to accumulate in the lungs and oxygen levels in the blood to be too low.
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Mechanical Ventilation
Jan 1, 2008
Mechanical ventilation is use of a machine to aid the movement of air into and out of the lungs.
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Introduction
Jan 1, 2008
Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle function are defective, leading to muscle weakness (see ) of varying severity. Other inherited muscle disorders include congenital myop...
Duchenne and Becker Muscular Dystrophies
Jan 1, 2008
Duchenne muscular dystrophy and Becker muscular dystrophy cause weakness in the muscles closest to the torso.
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Other Forms of Muscular Dystrophy
Jan 1, 2008
Several uncommon forms of muscular dystrophy, all inherited, also cause progressive muscle weakness....
Congenital Myopathies
Jan 1, 2008
Congenital myopathies is a term used to describe a wide variety of inherited disorders of the muscles, nerves, or both, which are present at birth or infancy.
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Periodic Paralysis
Jan 1, 2008
Periodic paralysis is an autosomal dominant inherited disorder (only one affected parent is needed to pass the trait on to offspring) that causes sudden attacks of weakness and paralysis. There are several forms.
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Overview of Head Injuries
Jan 1, 2008
The thick, hard bones of the skull help protect the brain from injury. Also, the brain is surrounded by layers of tissue (meninges) containing cerebrospinal fluid, which cushions the brain. Consequently, most bumps and knocks on the head do not injur...
Cerebral Contusions and Lacerations
Jan 1, 2008
Cerebral contusions are bruises on the brain, usually caused by a direct, strong blow to the head. Cerebral lacerations are tears in brain tissue, caused by a foreign object or pushed-i...
Concussion
Jan 1, 2008
A concussion is an injury-induced alteration in mental function or level of awareness that may involve a loss of consciousness, can occur without obvious damage to brain structures, and lasts less than 6 hours.
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Diffuse Axonal Injury
Jan 1, 2008
Diffuse axonal injury is widespread injury to axons, a part of the nerve cells in the brain.
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Intracranial Hematomas
Jan 1, 2008
Intracranial hematomas are accumulations of blood within the brain or between the brain and the skull.
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Skull Fracture
Jan 1, 2008
A skull fracture is a break in a bone surrounding the brain.
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Paget's Disease of Bone
Dec 1, 2007
Paget's disease of bone is a chronic disorder of the skeleton in which areas of bone undergo abnormal turnover, resulting in areas of enlarged and softened bone.
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Overview of Malabsorption
Dec 1, 2007
Malabsorption syndrome refers to a number of disorders in which nutrients from food are not absorbed properly in the small intestine.
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Lactose Intolerance
Dec 1, 2007
Lactose intolerance is the inability to digest the sugar lactose (which is present in all dairy products) because of a deficiency of the digestive enzyme lactase, leading to diarrhea and abdominal cramping.
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Celiac Sprue
Dec 1, 2007
Celiac sprue (nontropical sprue, gluten enteropathy, celiac disease) is a hereditary intolerance to gluten (a protein found in wheat, barley, and oats) that causes characteristic changes in the lining of the small intestine, resulting in mal...
Tropical Sprue
Dec 1, 2007
Tropical sprue is a disorder of unknown cause affecting people living in tropical and subtropical areas who develop abnormalities of the lining of the small intestine, leading to malabsorption and deficiencies of many nutrients.
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Whipple's Disease
Dec 1, 2007
Whipple's disease (intestinal lipodystrophy) is the result of a rare bacterial infection that damages the lining of the small intestine and may involve other organs of the body.
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Intestinal Lymphangiectasia
Dec 1, 2007
Intestinal lymphangiectasia (idiopathic hypoproteinemia) is a disorder in which the lymph vessels supplying the lining of the small intestine become enlarged and obstructed.
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Short Bowel Syndrome
Dec 1, 2007
Short bowel syndrome is a disorder causing diarrhea and poor absorption of nutrients (malabsorption), which often occurs after surgical removal of a large portion of the small intestine.
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Bacterial Overgrowth Syndrome
Dec 1, 2007
Bacterial overgrowth syndrome is a disorder in which poor movement of intestinal contents allows certain normal intestinal bacteria to grow excessively, causing diarrhea and poor absorption of nutrients (malabsorption).
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Esophageal Tumors That Are Noncancerous
Dec 1, 2007
Noncancerous (benign) tumors of the esophagus are rare and are usually more bothersome than harmful....
Esophageal Cancer
Dec 1, 2007
The most common types of esophageal cancer are squamous cell carcinoma and adenocarcinoma, which develop in the cells that line the wall of the esophagus. These cancers may develop anywhere in the esophagus and may appear as a narrowing (stricture) o...
Stomach Tumors That Are Noncancerous
Dec 1, 2007
Noncancerous (benign) tumors of the stomach are unlikely to cause symptoms or medical problems, so they often remain undiagnosed and untreated. Occasionally, however, some bleed and are then removed during endoscopy (in which a flexible viewing tube ...
Stomach Cancer
Dec 1, 2007
About 95% of stomach cancers are adenocarcinomas. Adenocarcinomas of the stomach originate from the glandular cells of the stomach lining....
Small-Intestine Tumors That Are Noncancerous
Dec 1, 2007
Most tumors of the small intestine are noncancerous (benign). These include tumors of fat cells (lipomas), nerve cells (neurofibromas), connective tissue cells (fibromas), and muscle cells (leiomyomas)....
Small-Intestine Cancer
Dec 1, 2007
Cancerous (malignant) tumors in the small intestine are very uncommon, occurring in fewer than 6,000 people in the United States each year. Adenocarcinoma is the most common type of cancer of the small intestine. Adenocarcinomas develop in the glandu...
Colorectal Polyps
Dec 1, 2007
A polyp is a growth of tissue from the intestinal or rectal wall that protrudes into the intestine or rectum and may be noncancerous (benign) or cancerous (malignant). Polyps vary considerably in size, and the bigger the polyp, the greater the risk t...
Colorectal Cancer
Dec 1, 2007
Almost all cancers of the large intestine and rectum (colorectal) are adenocarcinomas, which develop from the lining of the large intestine (colon) and rectum. Colorectal cancer usually begins as a buttonlike swelling on the surface of the intestinal...
Anal Cancer
Dec 1, 2007
Anal cancer develops in the skin cells of the immediate area around the anus or in the lining of the transitional zone between the anus and the rectum (the anal canal). Unlike in the rectum and the large intestine, in which cancers are almost always ...
Pancreatic Cancer
Dec 1, 2007
About 95% of cancerous (malignant) tumors of the pancreas are adenocarcinomas. Adenocarcinomas usually originate in the glandular cells lining the pancreatic duct. Most adenocarcinomas occur in the head of the pancreas, the part nearest the first seg...
Pancreatic Endocrine Tumors
Dec 1, 2007
Pancreatic endocrine tumors are those that arise from the types of pancreatic cells that produce hormones. These tumors may or may not secrete hormones themselves and may or may not be cancerous (malignant). Even if they do not secrete hormones (nonf...
Overview of Blood Vessel Disorders of the Liver
Dec 1, 2007
The liver receives the oxygen and nutrients it needs in blood that comes from two large blood vessels. The portal vein, provides about two thirds of the blood. This blood contains oxygen and many nutrients brought to the liver from the intes...
Ischemic Hepatitis
Dec 1, 2007
Ischemic hepatitis is damage throughout the liver caused by an inadequate blood or oxygen supply.
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Ischemic Cholangiopathy
Dec 1, 2007
Ischemic cholangiopathy is damage to one or more bile ducts caused by inadequate blood flow.
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Budd-Chiari Syndrome
Dec 1, 2007
Budd-Chiari syndrome is caused by blood clots that completely or partially block the large veins that carry blood from the liver (hepatic veins) into the inferior vena cava.
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Veno-Occlusive Disease of the Liver
Dec 1, 2007
Veno-occlusive disease of the liver is blockage of the very small (microscopic) veins in the liver.
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Portal Vein Thrombosis
Dec 1, 2007
Portal vein obstruction results from thrombosis (blood clot) or narrowing of the portal vein, which brings blood to the liver from the intestines.
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Congestive Hepatomegaly
Dec 1, 2007
Congestive hepatomegaly is a backup of blood in the liver, resulting from heart failure.
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Overview of Gallbladder and Bile Duct Disorders
Dec 1, 2007
The liver produces bile, a greenish yellow, thick, sticky fluid. Bile aids digestion by making cholesterol, fats, and fat-soluble vitamins easier to absorb from the intestine. Bile also helps eliminate certain waste products (mainly bilirubi...
Gallstones
Dec 1, 2007
Gallstones are collections of solid material (predominantly crystals of cholesterol) in the gallbladder.
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Cholecystitis
Dec 1, 2007
Cholecystitis is inflammation of the gallbladder, usually resulting from a gallstone blocking the cystic duct.
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Tumors of the Bile Ducts and Gallbladder
Dec 1, 2007
Cancer of the bile ducts (cholangiocarcinoma) can originate anywhere along the biliary tract, particularly outside of the liver to where it enters the small intestine. It can complicate primary sclerosing cholangitis (see )...
Overview of Blood Vessel Disorders of the Kidneys
Dec 1, 2007
The blood flow to the kidneys needs to be intact for the kidneys to function properly. Any interruption of or reduction in the blood flow can cause kidney damage or dysfunction and, if long-standing, increased blood pressure. When blood flow in the a...
Blockage of the Renal Arteries
Dec 1, 2007
There are two renal arteries—one supplies blood to the right kidney, the other to the left kidney. These arteries branch into many smaller arteries....
Atheroembolic Kidney Disease
Dec 1, 2007
In atheroembolic kidney disease, numerous small pieces of fatty material (atheroemboli) travel from arteries above the kidneys to clog the smallest branches of the renal arteries, causing the kidneys to fail.
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Renal Cortical Necrosis
Dec 1, 2007
Renal (kidney) cortical necrosis is death of the tissue in the outer part of kidney (cortex) that results from blockage of the small arteries that supply blood to the cortex and that causes acute kidney failure.
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Malignant Hypertensive Nephrosclerosis
Dec 1, 2007
In malignant hypertensive nephrosclerosis, severe high blood pressure (malignant hypertension) damages the smallest arteries in the kidneys, and kidney failure progresses rapidly.
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Renal Vein Thrombosis
Dec 1, 2007
Renal vein thrombosis is blockage of the renal vein, which carries blood away from the kidney, by a blood clot.
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Kidney Cancer
Dec 1, 2007
Kidney cancer accounts for about 2 to 3% of cancers in adults, affecting about 50% more men than women. Smokers are about twice as likely to develop kidney cancer as nonsmokers. Other risk factors include exposure to toxic chemicals and obesity. Peop...
Renal Pelvis and Ureter Cancer
Dec 1, 2007
Cancer can occur in the cells lining the central collecting area of the kidney (the renal pelvis—usually a type called transitional cell carcinoma of the renal pelvis) and in the slender tubes that carry urine from the kidney to the bladder (ureters)...
Bladder Cancer
Dec 1, 2007
An estimated 67,000 new cases of bladder cancer are diagnosed every year in the United States. About 3 times as many men as women develop bladder cancer. Smoking is the greatest single risk factor and seems to be one of the causes in at least half of...
Urethral Cancer
Dec 1, 2007
Cancer of the urethra (the channel that carries urine from the bladder out of the body) is rare, occurring most commonly after age 50. It can occur in men and women. Certain types of human papillomavirus are implicated as the cause of cancer of the u...
Refractive Disorders
Dec 1, 2007
In refractive disorders, the eye focuses light rays incorrectly on the retina, causing blurred vision.
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Gastroenteritis in Children
Dec 1, 2007
Gastroenteritis is inflammation of the digestive tract that results in vomiting, diarrhea, or both and is sometimes accompanied by fever or abdominal cramps.
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Gastroesophageal Reflux in Children
Dec 1, 2007
Gastroesophageal reflux is the backward movement of food and acid from the stomach into the esophagus and sometimes into the mouth (see ).
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Peptic Ulcer in Children
Dec 1, 2007
A peptic ulcer is erosion of the lining of the stomach or small intestine (duodenum) due to excess stomach acid, breakdown of the stomach's protective lining, or both.
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Hernia in Children
Dec 1, 2007
A hernia is a protrusion of a piece of the intestine through an abnormal opening.
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Hypertrophic Pyloric Stenosis
Dec 1, 2007
Hypertrophic pyloric stenosis is blockage of the passage out of the stomach due to overdevelopment (hypertrophy) of the muscle at the junction between the stomach and the intestines.
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Intussusception
Dec 1, 2007
Intussusception is a disorder in which one segment of the intestine slides into another, much like the parts of a telescope. The affected segments obstruct the bowel and block blood flow.
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Appendicitis in Children
Dec 1, 2007
Appendicitis is inflammation and infection of the appendix.
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Meckel's Diverticulum
Dec 1, 2007
Meckel's diverticulum is a saclike outpouching of the wall of the small intestine present in some children at birth.
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Constipation in Children
Dec 1, 2007
Constipation refers to delay or difficulty in passing stool or an increase in the hardness and size of stool.
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Chronic and Recurring Abdominal Pain
Dec 1, 2007
Chronic and recurring abdominal pain occurs for more than 3 months and interferes with the child's life.
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Introduction
Nov 1, 2007
Drug administration is the giving of a drug by one of several means (routes). Drug kinetics (pharmacokinetics) involves what the body does to a drug, including the processes of absorption, distribution, metabolism, and elimination...
Drug Administration
Nov 1, 2007
Drugs are introduced into the body by several routes. They may be taken by mouth (orally); given by injection into a vein (intravenously), into a muscle (intramuscularly), into the space around the spinal cord (intrathecally), or beneath the skin (su...
Drug Absorption
Nov 1, 2007
Drug absorption is the movement of a drug into the bloodstream.
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Drug Distribution
Nov 1, 2007
Drug distribution refers to the movement of a drug to and from the blood and various tissues of the body (for example, fat, muscle, and brain tissue) and the relative proportions of drug in the tissues.
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Drug Metabolism
Nov 1, 2007
Drug metabolism is the chemical alteration of a drug by the body.
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Drug Elimination
Nov 1, 2007
Drug elimination is the removal of drugs from the body.
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Definition of Drug Dynamics
Nov 1, 2007
Drug dynamics (pharmacodynamics) involves what a drug does to the body.
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Site Selectivity
Nov 1, 2007
After being swallowed, injected, inhaled, or absorbed through the skin, most drugs enter the bloodstream and circulate throughout the body. Some drugs are administered directly to the area where they are wanted—for example, to the eyes in eyedrops. T...
Drug Action
Nov 1, 2007
Drugs affect only the rate at which existing biologic functions proceed. Drugs do not change the basic nature of these functions or create new functions. For example, drugs can speed up or slow down the biochemical reactions that cause muscles to con...
Sleep Apnea
Nov 1, 2007
Sleep apnea is a serious disorder in which breathing repeatedly stops long enough to disrupt sleep and temporarily decrease the amount of oxygen and increase the amount of carbon dioxide in the blood.
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Overview of the Nervous System
Nov 1, 2007
The nervous system has two distinct parts: the central nervous system (the brain and spinal cord) and the peripheral nervous system (the nerves outside the brain and spinal cord)....
Brain
Nov 1, 2007
The brain's functions are both mysterious and remarkable. All thoughts, beliefs, memories, behaviors, and moods arise within the brain. The brain is the site of thinking and the control center for the rest of the body. The brain coordinates the abili...
Spinal Cord
Nov 1, 2007
The spinal cord is a long, fragile tubelike structure that begins at the end of the brain stem and continues down almost to the bottom of the spine (spinal column). The spinal cord consists of nerves that carry incoming and outgoing messages between ...
Nerves
Nov 1, 2007
The peripheral nervous system consists of more than 100 billion nerve cells that run throughout the body like strings, making connections with the brain, other parts of the body, and often with each other. Peripheral nerves consist of bundles of nerv...
Effects of Aging on the Nervous System
Nov 1, 2007
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Overview of Stroke
Nov 1, 2007
A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue (cerebral infarction) and causing sudden symptoms.
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Transient Ischemic Attacks
Nov 1, 2007
A transient ischemic attack (TIA) is a disturbance in brain function that lasts less than 1 hour and results from a temporary blockage of the brain's blood supply.
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Ischemic Stroke
Nov 1, 2007
An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery.
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Hemorrhagic Stroke
Nov 1, 2007
Hemorrhagic strokes include bleeding within the brain (intracerebral hemorrhage) and bleeding between the inner and outer layers of the tissue covering the brain (subarachnoid hemorrhage).
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Overview of Sexuality
Nov 1, 2007
Sexuality is a normal part of human experience. However, the types of sexual behavior that are considered normal vary greatly within and among different cultures. In fact, defining “normal” sexuality may be impossible. There are wide variations in pe...
Gender Identity
Nov 1, 2007
Gender identity is how people see themselves, whether masculine, feminine, or somewhere in-between. Gender role is how people present themselves in public in terms of gender. It includes the way people dress, speak, wear their hair, in fact everythin...
Paraphilias
Nov 1, 2007
Paraphilias are frequent, intense, sexually arousing fantasies or behaviors that involve inanimate objects, children or nonconsenting adults, or suffering or humiliation of oneself or the partner.
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Definition of Diverticular Disease
Nov 1, 2007
Diverticular disease is characterized by small, balloon-like sacs (diverticula) protruding through the muscular layer of the gastrointestinal (digestive) tract.
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Diverticulosis
Nov 1, 2007
Diverticulosis is the presence of multiple balloon-like sacs (diverticula), usually in the large intestine.
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Diverticulitis
Nov 1, 2007
Diverticulitis is inflammation or infection of one or more balloon-like sacs (diverticula).
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Dialysis
Nov 1, 2007
Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly.
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Overview of the Adrenal Glands
Nov 1, 2007
The body has two adrenal glands, one near the top of each kidney. The inner part (medulla) of the adrenal glands secretes hormones, such as adrenaline (epinephrine), that help control blood pressure, heart rate, sweating, and other activities also re...
Addison's Disease
Nov 1, 2007
In Addison's disease, the adrenal glands are underactive, resulting in a deficiency of adrenal hormones.
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Cushing's Syndrome
Nov 1, 2007
In Cushing's syndrome, the level of corticosteroids is excessive, usually from overproduction by the adrenal glands.
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Virilization
Nov 1, 2007
Virilization is the development of exaggerated masculine characteristics, usually in women, often as a result of the adrenal glands overproducing androgens (testosterone and similar hormones).
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Hyperaldosteronism
Nov 1, 2007
In hyperaldosteronism, overproduction of aldosterone leads to fluid retention and increased blood pressure, weakness, and, rarely, periods of paralysis.
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Pheochromocytoma
Nov 1, 2007
A pheochromocytoma is a tumor that usually originates from the adrenal glands' chromaffin cells, causing overproduction of catecholamines, powerful hormones that induce high blood pressure and other symptoms.
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Overview of Rickettsial Infections
Nov 1, 2007
Rickettsial infections and related infections (such as ehrlichiosis and Q fever) are caused by an unusual type of bacteria that can live only in another organism.
...
Rocky Mountain Spotted Fever
Nov 1, 2007
Rocky Mountain spotted fever (spotted fever, tick fever, tick typhus) is a rickettsial infection that is transmitted by dog ticks and wood ticks. It causes a rash, headache, and high fever.
...
Ehrlichioses
Nov 1, 2007
Ehrlichioses are tick-borne infections that cause fever, chills, headache, and a general feeling of illness (malaise). These symptoms begin suddenly.
...
Overview of the Eyelids and Tears
Nov 1, 2007
The eyelids play a key role in protecting the eyes. They sweep away debris when the eyes close and help spread moisture (tears) over the surface of the eyes when they open. The eyelids provide a mechanical barrier against injury by closing rapidly wh...
Blepharitis
Nov 1, 2007
Blepharitis is inflammation of the edges of the eyelids, possibly with thickening scales, crusts, shallow ulcers, or redness and swelling at the edges of the eyelids.
...
Canaliculitis
Nov 1, 2007
Canaliculitis is infection of the lacrimal canaliculus, also called the lacrimal duct (see ).
...
Chalazion
Nov 1, 2007
A chalazion is an enlargement of an oil gland deep in the eyelid caused by an obstruction of the gland's opening.
...
Dacryocystitis
Nov 1, 2007
Dacryocystitis is infection of the lacrimal sac.
...
Dacryostenosis
Nov 1, 2007
Dacryostenosis (nasolacrimal duct obstruction) is narrowing of the nasolacrimal duct, which drains tears away from the eye.
...
Entropion and Ectropion
Nov 1, 2007
Entropion is a condition in which the eyelid is turned inward (inverted), causing the eyelashes to rub against the eyeball. Ectropion is a condition in which the eyelid is turned outward (everted) so that its edge does not touch t...
Eyelid Tumors
Nov 1, 2007
Noncancerous (benign) and cancerous (malignant) growths can form on the eyelids. One of the most common types of benign tumor is xanthelasma, a yellow-white, flat growth that consists of fatty material. Because xanthelasmas may indicate elevated chol...
Stye (Hordeolum)
Nov 1, 2007
A stye (hordeolum) is a rapidly developing infection of one or more of the tiny glands at the edge of the eyelid or underneath the eyelid that sometimes develops a small abscess.
...
Trichiasis
Nov 1, 2007
Trichiasis is misalignment of eyelashes, which rub against the eyeball, in a person who does not have entropion.
...
Detecting and Dating a Pregnancy
Nov 1, 2007
If a menstrual period is a week or more late in a woman who usually has regular menstrual periods, she may be pregnant. Sometimes a woman may guess she is pregnant because she has typical symptoms. They include the following:...
Stages of Development of the Fetus
Nov 1, 2007
A baby goes through several stages of development, beginning as a fertilized egg. The egg develops into a blastocyst, an embryo, then a fetus....
Physical Changes During Pregnancy
Nov 1, 2007
Pregnancy causes many changes in a woman's body. Most of them disappear after delivery. These changes cause some symptoms, which are normal. However, certain disorders, such as gestational diabetes (see ), develop during pregnancy, and some symptoms ...
Medical Care During Pregnancy
Nov 1, 2007
Ideally, a couple who is thinking of having a baby should see a doctor or other health care practitioner to discuss whether pregnancy is advisable. Usually, pregnancy is very safe. However, some disorders can become severe during pregnancy. Also, for...
Self-Care During Pregnancy
Nov 1, 2007
There is much a pregnant woman can do to take care of herself during pregnancy. If she has any questions about diet, the use of drugs or nutritional supplements, physical activity, and sexual intercourse during pregnancy, she can talk with her doctor...
Introduction
Oct 1, 2007
A century ago, most people who suffered major injuries or contracted serious infections died soon afterward. Most people expected little more than comfort measures from doctors. Today, because medical procedures commonly extend the lives of people wh...
Time Course of Dying
Oct 1, 2007
A prognosis is a prediction of the probable course and outcome of a disease or the likelihood of recovery from a disease. People often think that the doctor knows and can predict how long an ill person will live but is withholding this information fr...
Choices to Make Before Death
Oct 1, 2007
Sick people and their families may feel swept along by the fatal illness and the various treatments, as if they have no control over the events. Some people seem to prefer this sense of having no control because it relieves them of the responsibility...
Treatment Options at the End of Life
Oct 1, 2007
...
Hospice Care
Oct 1, 2007
Hospice is a concept and a program of care that is specifically designed to minimize suffering for dying people and their family members. In the United States, hospice is the only widely available comprehensive program to support very sick people at ...
Symptoms During a Fatal Illness
Oct 1, 2007
Many fatal illnesses cause similar symptoms, including pain, shortness of breath, digestive problems, incontinence, skin breakdown, and fatigue. Depression, anxiety, confusion, unconsciousness, and disability may also occur....
Financial Concerns at the End of Life
Oct 1, 2007
Medicare does not pay for some services dying people need, such as long-term care in nursing homes or home health aides at home. Services provided by a hospice program are the exception in that they are usually quite comprehensive. However, hospice p...
Legal and Ethical Concerns at the End of Life
Oct 1, 2007
...
Acceptance of Death and Dying
Oct 1, 2007
Preparing for death often means finishing a life's work, setting things right with family and friends, and making peace with the inevitable. Spiritual and religious issues are important to many dying people and their families. Members of the clergy a...
When Death Is Near
Oct 1, 2007
At some point, deciding not to undergo cardiopulmonary resuscitation (CPR—an emergency procedure that restores heart and lung function) is appropriate for virtually all people who are dying and who can accept death. Dying people, families, and the ca...
When Death Occurs
Oct 1, 2007
Death must be pronounced in an official and timely way by an authorized person (such as a doctor or nurse), and the cause and circumstances of death must be certified. Fulfilling these requirements varies substantially in different parts of the Unite...
Overview of Legal and Ethical Issues in Health Care
Oct 1, 2007
The law has a lot to say about personal decision-making. For example, people have the legal right to make their own health care decisions. However, poor health can jeopardize people's ability to defend their legal rights. Safeguarding these rights re...
Capacity to Make Health Care Decisions
Oct 1, 2007
The law recognizes that adults—in most states, people over age 18—have the right to manage their own affairs and conduct business, including the right to make health care decisions. Emancipated minors are people below the age of adulthood (usually 18...
Informed Consent
Oct 1, 2007
Before performing any invasive tests or providing medical treatment, doctors must obtain permission from the patient in a manner that is informed, voluntary, and competent. The process is known as informed consent. People have the right to informatio...
Confidentiality and HIPAA
Oct 1, 2007
Health care practitioners have a duty to keep personal medical information confidential. Communication between the patient and doctor is strictly confidential. Even well-meaning family members are not necessarily allowed to have information about a p...
Advance Directives
Oct 1, 2007
Health care advance directives are documents that communicate a person's wishes about health care decisions in the event the person becomes incapable of making health care decisions. There are two basic kinds of advance directives: living wills and d...
Surrogate Decision Making
Oct 1, 2007
If a person is unable to make decisions about personal health care, some other person or persons must provide direction in decision making. Such a person is called the surrogate decision maker. If there is a durable power of attorney for health care,...
Do-Not-Resuscitate (DNR) Orders
Oct 1, 2007
A do-not-resuscitate (DNR) order placed in a person's medical record by a doctor informs the medical staff that cardiopulmonary resuscitation (CPR—see ) should not be performed. This order has been useful in preventing unnecessary and unwanted invasi...
Medical Malpractice
Oct 1, 2007
People can sue health care practitioners if they feel they have been injured. A wide variety of causes of action and legal proceedings may be involved. However, successful medical malpractice lawsuits generally require proof of all of the following:...
Introduction
Oct 1, 2007
A neurologic examination can detect disorders of the brain, spinal cord, and nerves in other parts of the body (peripheral nerves, which include motor and sensory nerves). This examination can also help detect muscle disorders because muscle contract...
Medical History
Oct 1, 2007
Before doing a physical examination, doctors interview the person. Doctors ask the person to describe current symptoms:...
Physical Examination
Oct 1, 2007
When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. They do a neurologic examination, which includes evaluation of mental status, cranial ner...
Tests for Brain, Spinal Cord, and Nerve Disorders
Oct 1, 2007
Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and physical examination. Imaging tests such as computed tomography (CT—see ), magnetic resonance imaging (MRI—see ), angiography (see ), positron emission to...
Introduction
Oct 1, 2007
Dizziness is a vague term used to describe various sensations, including faintness, light-headedness, a loss of balance, a sense of spinning, a vague spaced-out feeling, and weakness. Vertigo is a specific type of dizziness. In vertigo, people feel a...
Dizziness
Oct 1, 2007
Dizziness accounts for about 5 to 6% of visits to the doctor. It may occur at any age but becomes more common as people age. It affects about 40% of people older than 40 at some time. At any age, dizziness can cause problems, particularly when doing ...
Vertigo
Oct 1, 2007
Vertigo is a false sensation that the self, the surroundings, or both are moving or spinning, usually accompanied by nausea and loss of balance.
...
Motion Sickness
Oct 1, 2007
Motion sickness (also known as car, sea, train, or air sickness) involves a group of symptoms, particularly nausea, caused by movement during travel.
...
Benign Paroxysmal Positional Vertigo (Benign Positional Vertigo)
Oct 1, 2007
Benign paroxysmal positional vertigo, or BPPV, is a common disorder causing short episodes of vertigo in response to changes in head position that stimulate the posterior semicircular canal of the inner ear.
...
Overview of the Esophagus
Oct 1, 2007
The esophagus is the hollow tube that leads from the throat (pharynx) to the stomach. The walls of the esophagus propel food to the stomach not by gravity, but by rhythmic waves of muscular contractions called peristalsis....
Abnormal Propulsion of Food
Oct 1, 2007
The movement of food from mouth to stomach requires normal and coordinated action of the mouth and throat, propulsive waves of the esophagus, and relaxation of the sphincters. A problem with any of these functions can cause difficulty swallowing (dys...
Infection of the Esophagus
Oct 1, 2007
Infection of the esophagus occurs mainly in people who have impaired host defenses. The main causes are Candida albicans, herpes simplex virus infections, and cytomegalovirus infection.
...
Injury to the Esophagus
Oct 1, 2007
The esophagus is relatively impervious to injury but can be harmed gradually by backflow of acid from the stomach (gastroesophageal reflux or GERD—see ). The esophagus may also be harmed suddenly, by caustic or acidic chemicals, irritating drugs, a s...
Obstruction of the Esophagus
Oct 1, 2007
The esophagus can be narrowed or completely blocked. In rare cases, the cause is hereditary (for example, congenital rings). In most cases, the cause is progression of an injury to the esophagus or tumor growth. Food and foreign bodies may obstruct t...
Overview of Kidney Failure
Oct 1, 2007
Kidney (renal) failure is the inability of the kidneys to adequately filter metabolic waste products from the blood.
...
Acute Kidney Failure
Oct 1, 2007
Acute kidney failure is a rapid (days to weeks) decline in the kidneys' ability to filter metabolic waste products from the blood.
...
Chronic Kidney Failure
Oct 1, 2007
Chronic kidney failure (also called chronic kidney disease) is a slowly progressive (months to years) decline in the kidneys' ability to filter metabolic waste from the blood.
...
Urinary Incontinence
Oct 1, 2007
Urinary incontinence is the uncontrollable loss of urine.
...
Urinary Incontinence in Children
Oct 1, 2007
Incontinence in children has different causes and treatment than that in adults. Incontinence can occur at night (bed-wetting, also called nocturnal enuresis—see ). Nocturnal enuresis is more common among boys, and children usually outgrow this type ...
Introduction
Oct 1, 2007
Sweat is made by sweat glands in the skin and carried to the skin's surface by ducts. Sweating helps keep the body cool. Thus, people sweat more when it is warm. They also sweat when they are nervous, under stress, or exercising....
Prickly Heat
Oct 1, 2007
Prickly heat (miliaria) is an itchy skin rash caused by trapped sweat.
...
Excessive Sweating
Oct 1, 2007
People with excessive sweating (hyperhidrosis) sweat profusely, and some sweat almost constantly. Although people with a fever or those exposed to very warm environments sweat, people with excessive sweating tend to sweat even without these circumsta...
Diminished Sweating
Oct 1, 2007
Some people sweat too little (a condition called hypohidrosis). Diminished sweating is usually limited to a specific area of the body. It can be caused by a skin injury (such as from trauma, radiation, infection [such as leprosy], or inflammation) or...
Overview of Bacterial Skin Infections
Oct 1, 2007
The skin provides a remarkably good barrier against bacterial infections. Although many bacteria come in contact with or reside on the skin, they are normally unable to establish an infection. When bacterial skin infections do occur, they can range i...
Cellulitis
Oct 1, 2007
Cellulitis is a spreading bacterial infection of the skin and the tissues immediately beneath the skin.
...
Erysipelas
Oct 1, 2007
Erysipelas is a superficial form of cellulitis typically caused by streptococci.
...
Erythrasma
Oct 1, 2007
Erythrasma is infection of the top layers of the skin caused by the bacterium Corynebacterium minutissimum.
...
Folliculitis and Skin Abscesses
Oct 1, 2007
Folliculitis and skin abscesses are pus-filled pockets in the skin resulting from bacterial infection. They may be superficial or deep, affecting just hair follicules or deeper structures within the skin.
...
Hidradenitis Suppurativa
Oct 1, 2007
Hidradenitis suppurativa is inflammation of the apocrine sweat glands, resulting in painful accumulations of pus under the skin.
...
Impetigo
Oct 1, 2007
Impetigo is a skin infection, caused by Staphylococcus aureus, Streptococcus pyogenes, or both, that leads to the formation of scabby, yellow-crusted sores and, sometimes, small blisters filled with yellow fluid.
...
Lymphadenitis
Oct 1, 2007
Lymphadenitis is inflammation of one or more lymph nodes, which usually become swollen and tender.
...
Lymphangitis
Oct 1, 2007
Lymphangitis is inflammation of one or more lymphatic vessels, usually caused by a streptococcal infection.
...
Necrotizing Skin Infections
Oct 1, 2007
Necrotizing skin infections, including necrotizing cellulitis and necrotizing fasciitis, are severe forms of cellulitis characterized by death of infected tissue (necrosis).
...
Staphylococcal Scalded Skin Syndrome
Oct 1, 2007
Staphylococcal scalded skin syndrome is a reaction to a staphylococcal skin infection in which the skin blisters and peels off as though burned.
...
Overview of Preventive Care
Sep 1, 2007
Traditional medical care focuses on improving health by identifying and treating health problems that have already produced symptoms or complications. In contrast, preventive medical care focuses on preventing health problems from occurring. Preventi...
Tools of Prevention
Sep 1, 2007
Prevention includes four major tools. One tool is establishing a healthful lifestyle, which includes habits such as wearing a seat belt, eating a healthy diet, getting enough physical exercise, wearing sunscreen, and not smoking. Another tool is gett...
Prevention in Pregnant Women
Sep 1, 2007
Prenatal care is focused on recognizing and preventing problems that can complicate pregnancy (see ). For example, pregnant women are screened for high blood pressure, diabetes, sexually transmitted diseases, RhO(D) blood incompatibility (which can c...
Prevention in Older Adults
Sep 1, 2007
The goals of prevention in an older adult usually depend on the person's health, level of function, and risk profile. For example, a healthy, independent person with no serious disorders may focus mainly on preventing disorders from developing. A per...
Benefits of Exercise
Sep 1, 2007
Regular exercise makes the heart stronger and the lungs fitter, enabling the cardiovascular system to deliver more oxygen to the body with every heartbeat and the pulmonary system to increase the maximum amount of oxygen that the lungs can take in. E...
Starting an Exercise Program
Sep 1, 2007
People should consult their doctors before beginning competitive sports or an exercise program. Doctors ask about known medical disorders in the person and family members and symptoms the person has. They do a physical examination, including listenin...
Exercising Safely
Sep 1, 2007
Exercising without proper safety precautions often leads to injury. Scheduling workouts 48 hours apart, to allow muscles to recover, and keeping workouts varied in regard to exercise method and equipment choices may help prevent muscle overuse and re...
Choosing the Right Exercise
Sep 1, 2007
There are many forms of exercise, and each type has its advantages and disadvantages. Some people prefer to exercise in a gym or at home, whereas others prefer to exercise outdoors. Some people have a very structured exercise routine, whereas others ...
Overview of Gastroenteritis
Sep 1, 2007
Gastroenteritis is inflammation of the lining of the stomach and small and large intestines. It is usually caused by infection with a microorganism but can also be caused by ingestion of chemical toxins or drugs.
...
Hemorrhagic Colitis
Sep 1, 2007
Hemorrhagic colitis is a type of gastroenteritis in which certain strains of the bacterium Escherichia coli (E. coli) infect the large intestine and produce a toxin (Shiga toxin) that causes bloody diarrhea and other serious complications.
...
Staphylococcal Food Poisoning
Sep 1, 2007
Staphylococcal food poisoning results from eating food contaminated with toxins produced by certain types of staphylococci, resulting in diarrhea and vomiting.
...
Clostridium perfringens Food Poisoning
Sep 1, 2007
Clostridium perfringens food poisoning results from eating food contaminated by the bacterium Clostridium perfringens. Once in the small intestine, the bacterium releases a toxin that often causes diarrhea.
...
Traveler's Diarrhea
Sep 1, 2007
Traveler's diarrhea (turista) is characterized by diarrhea, nausea, and vomiting that commonly occur in travelers to areas of the world with poor water purification.
...
Chemical Food Poisoning
Sep 1, 2007
Chemical food poisoning results from eating a plant or animal that contains a toxin.
...
Overview of Gastrointestinal Emergencies
Sep 1, 2007
Certain gastrointestinal disorders can be life threatening and require emergency treatment—surgery, in many cases....
Abdominal Abscesses
Sep 1, 2007
An abscess is a pocket of pus, usually caused by a bacterial infection.
...
Abdominal Wall Hernias
Sep 1, 2007
An abdominal wall hernia is a protrusion of the intestine through an opening or area of weakness in the abdominal wall.
...
Acute Mesenteric Ischemia
Sep 1, 2007
Acute mesenteric ischemia is sudden blockage of blood flow to part of the intestines, which may lead to gangrene and perforation (puncture).
...
Appendicitis
Sep 1, 2007
Appendicitis is inflammation and infection of the appendix.
...
Ileus
Sep 1, 2007
Ileus (paralytic ileus, adynamic ileus) is temporary absence of the normal contractile movements of the intestinal wall.
...
Intestinal Obstruction
Sep 1, 2007
An obstruction of the intestine is a blockage that completely stops or seriously impairs the passage of intestinal contents.
...
Ischemic Colitis
Sep 1, 2007
Ischemic colitis is injury of the large intestine that results from an interruption of its blood supply.
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Perforation of the Digestive Tract
Sep 1, 2007
Any of the hollow digestive organs may become perforated (punctured), which causes a release of gastrointestinal contents and leads to shock and death if surgery is not performed immediately.
...
Overview of Cirrhosis and Fibrosis of the Liver
Sep 1, 2007
Most liver diseases, including fatty liver, cirrhosis, primary biliary cirrhosis and primary sclerosing cholangitis, result from injury to the liver. If damage is acute (sudden) and limited, the liver commonly repairs itself by regenerating new liver...
Fatty Liver
Sep 1, 2007
Fatty liver (steatosis) is an abnormal accumulation of certain fats (triglycerides) inside liver cells.
...
Cirrhosis
Sep 1, 2007
Cirrhosis is the irreversible replacement of a large amount of normal liver tissue with nonfunctioning scar tissue. It develops because the liver is damaged. Attempts at regenerating new liver cells are not effective.
...
Primary Biliary Cirrhosis
Sep 1, 2007
Primary biliary cirrhosis is inflammation with progressive scarring of the bile ducts in the liver. Eventually, the ducts are blocked, the liver becomes scarred, and liver failure develops.
...
Primary Sclerosing Cholangitis
Sep 1, 2007
Primary sclerosing cholangitis is inflammation with progressive scarring and narrowing of the bile ducts in and outside the liver. Eventually, the ducts become blocked and then obliterated. Cirrhosis, liver failure, and sometimes bile duct c...
Overview of Liver Tumors
Sep 1, 2007
Liver tumors may be noncancerous (benign) or cancerous (malignant). Cancerous liver tumors are classified as primary (originating in the liver) or metastatic (spreading from elsewhere in the body). Most liver cancers are metastatic. Cancers often spr...
Hemangiomas of the Liver
Sep 1, 2007
A hemangioma is a noncancerous liver tumor composed of a mass of abnormal blood vessels.
...
Hepatocellular Adenoma
Sep 1, 2007
A hepatocellular adenoma is a relatively uncommon noncancerous liver tumor that may be mistaken for cancer. Rarely, it ruptures and bleeds or becomes cancerous.
...
Hepatic Granulomas
Sep 1, 2007
Hepatic granulomas are abnormal small clumps of cells that form when certain disorders are present.
...
Primary Liver Cancers
Sep 1, 2007
Primary liver cancers are cancers that originate in the liver. The most common is a hepatoma (hepatocellular carcinoma). At first, liver cancer usually causes only vague symptoms (such as weight loss, loss of appetite, and fatigue). As a result, the ...
Metastatic Liver Cancer
Sep 1, 2007
Metastatic liver cancer is a cancer that has spread to the liver from elsewhere in the body.
...
Overview of Urinary Tract Infections
Sep 1, 2007
In healthy people, urine in the bladder is sterile—no bacteria or other infectious organisms are present. The tube that carries urine from the bladder out of the body (urethra) contains no bacteria or too few to cause an infection. However, any part ...
Urethritis
Sep 1, 2007
Urethritis is infection of the urethra, the tube that carries urine from the bladder out of the body.
...
Bladder Infection (Cystitis)
Sep 1, 2007
Cystitis is infection of the bladder.
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Kidney Infection (Pyelonephritis)
Sep 1, 2007
Pyelonephritis is a bacterial infection of one or both kidneys.
...
Asymptomatic Bacteriuria
Sep 1, 2007
Asymptomatic bacteriuria is a condition in which larger than normal numbers of bacteria are present in the urine but symptoms do not result.
...
Overview of Sexual Dysfunction in Men
Sep 1, 2007
In men, sexual dysfunction refers to difficulties engaging in sexual intercourse. Sexual dysfunction encompasses a variety of disorders that affect sex drive (libido), the ability to achieve or maintain an erection (erectile dysfunction, or impotence...
Decreased Libido in Men
Sep 1, 2007
Decreased libido is a reduction in sex drive.
...
Erectile Dysfunction (ED)
Sep 1, 2007
Erectile dysfunction (impotence) is the inability to achieve or maintain an erection adequate for penetration.
...
Inability to Ejaculate
Sep 1, 2007
Inability to ejaculate (anejaculation) is usually caused by inability to reach orgasm. It usually occurs as part of erectile dysfunction. Causes, diagnosis, and treatment are the same as for erectile dysfunction (see ). Retrograde ejaculation can som...
Premature Ejaculation
Sep 1, 2007
Premature ejaculation is ejaculation that occurs too early, usually before, upon, or shortly after penetration.
...
Retrograde Ejaculation
Sep 1, 2007
Retrograde ejaculation is a condition in which semen is ejaculated backward into the bladder rather than out through the penis.
...
Definition of Violence Against Women
Sep 1, 2007
Violence against women is broadly defined as any act that is likely to cause physical, sexual, or psychologic harm or extreme suffering to a woman. Violence can occur in the home, workplace, or community. Two common forms of violence against women ar...
Domestic Violence
Sep 1, 2007
Domestic violence includes physical, sexual, and psychologic abuse between people who live together, including intimate partners, parents and children, children and grandparents, and siblings. It occurs among people of all cultures, races, occupation...
Rape
Sep 1, 2007
Rape refers to unwanted penetration of the vagina, anus, or mouth....
Chromosomes and Genes
Aug 1, 2007
Proteins are probably the most important class of material in the body. Proteins are not just building blocks for muscles, connective tissues, skin, and other structures. They also are needed to make enzymes. Enzymes are complex pro...
Inheritance of Single-Gene Disorders
Aug 1, 2007
The traits produced by a gene can be characterized as dominant or recessive. Dominant traits can be expressed when only one copy of the gene for that trait is present. Recessive traits carried on autosomal chromosomes can be expressed only when two c...
Gene Technology
Aug 1, 2007
Gene technology is rapidly improving. The polymerase chain reaction (PCR) is a laboratory technique that can produce large numbers of copies of a gene, which makes studying the gene much easier. A specific segment of deoxyribonucleic acid (DNA), such...
Uses of Genetics
Aug 1, 2007
The potential for understanding human genetics increased greatly when the Human Genome Project successfully identified and mapped all the genes on human chromosomes in 2003. Genetic techniques can be used to study individual genes to learn more about...
Gene Therapy
Aug 1, 2007
Although gene therapy is defined as any treatment that changes gene function, it is often thought of as the insertion of normal genes into the cells of a person who lacks such normal genes because of a specific genetic disorder (gene insertion therap...
Ethical Controversies in Genetics
Aug 1, 2007
With the new genetic diagnostic and therapeutic capabilities come many controversies about how they should be used. Concerns have been raised that knowledge of a person's genetic information might be used improperly. For instance, people whose geneti...
Overview of Adverse Drug Reactions
Aug 1, 2007
In the early 1900s, German scientist Paul Ehrlich described an ideal drug as a "magic bullet." Such a drug would be aimed precisely at a disease site and would not harm healthy tissues. Although many new drugs are aimed more accurately than their pre...
Types of Adverse Drug Reactions
Aug 1, 2007
Many adverse drug reactions represent an exaggeration of the drug's therapeutic effects (called type 1 or overdose reactions). For example, a person taking a drug to reduce high blood pressure may feel dizzy or light-headed if the drug reduces blood ...
Severity of Adverse Drug Reactions
Aug 1, 2007
There is no universal scale for describing or measuring the severity of an adverse drug reaction. Assessment is largely subjective. Reactions can be described as mild, moderate, severe, or lethal....
Benefits Versus Risks of Drugs
Aug 1, 2007
Every drug has the potential to do harm as well as good. When doctors consider prescribing a drug, they must weigh the possible risks against the expected benefits. Use of a drug is not justified unless the expected benefits outweigh the possible ris...
Risk Factors for Adverse Drug Reactions
Aug 1, 2007
Many factors can increase the likelihood of an adverse drug reaction. They include the simultaneous use of several drugs, very young or old age, pregnancy, and breastfeeding. Hereditary factors make some people more susceptible to the toxic effects o...
Allergies to Drugs
Aug 1, 2007
People sometimes mistake many adverse drug reactions for allergies. For example, people who experience stomach discomfort after taking aspirin (a common adverse reaction) often say they are "allergic" to aspirin. However, this is not a true allergic ...
Overdose Toxicity
Aug 1, 2007
Overdose toxicity refers to serious, often harmful, and sometimes fatal toxic reactions to an accidental overdose of a drug (because of a doctor's, pharmacist's, or patient's error) or to an intentional overdose (homicide or suicide)....
Pulmonary Embolism
Aug 1, 2007
Pulmonary embolism is the sudden blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or rarely other foreign material.
...
Overview of Pain
Aug 1, 2007
Pain is an unpleasant sensation signaling actual or possible injury.
...
Types of Pain
Aug 1, 2007
There are several types of pain, including neuropathic pain (such as sciatica—see ), nociceptive pain (such as pain after surgery and pain due to cancer), and psychogenic pain....
Evaluation of Pain
Aug 1, 2007
Neither examinations nor tests can prove that a person is in pain. Consequently, doctors ask the person about the history and characteristics of pain. The person's answers help them identify the cause and develop a treatment strategy. Questions can i...
Treatment of Pain
Aug 1, 2007
In some cases, treating the underlying disorder eliminates or minimizes the pain. For example, setting a broken bone in a cast or giving antibiotics for an infected joint helps reduce pain. However, even if the underlying disorder can be treated, pai...
Overview of Movement Disorders
Aug 1, 2007
Every body movement, from raising a hand to smiling, involves a complex interaction between the central nervous system (brain and spinal cord), nerves, and muscles. Damage to or malfunction of any of these components may result in a movement disorder...
Myoclonus
Aug 1, 2007
Myoclonus refers to quick, lightning-like jerks (contractions) of a muscle or a group of muscles.
...
Tremor
Aug 1, 2007
A tremor is an involuntary, rhythmic, shaking movement produced when muscles repeatedly contract and relax.
...
Parkinson's Disease
Aug 1, 2007
Parkinson's disease is a slowly progressive degenerative disorder of the central nervous system. It is characterized by tremor when muscles are at rest (resting tremor), increased muscle tone (rigidity), slowness of voluntary movements, and ...
Parkinsonism
Aug 1, 2007
Parkinsonism refers to symptoms of Parkinson's disease (such as slow movements and tremors) that are caused by another condition.
...
Progressive Supranuclear Palsy
Aug 1, 2007
Progressive supranuclear palsy is characterized by muscle stiffness (rigidity), inability to move the eyes, weakness of the throat muscles, and a tendency to fall backward.
...
Multiple System Atrophy
Aug 1, 2007
Multiple system atrophy is a progressive, fatal disorder that makes muscles stiff (rigid) and causes problems with movement, loss of coordination, and malfunction of internal body processes (such as blood pressure and bladder control).
...
Tics
Aug 1, 2007
Tics are rapid, purposeless, repetitive but not rhythmic involuntary movements that are virtually identical to one another. They can be suppressed but only for a short time and only with conscious effort.
...
Chorea, Athetosis, and Hemiballismus
Aug 1, 2007
Chorea is repetitive, brief, jerky, rapid involuntary movements that start in one part of the body and move abruptly, unpredictably, and often continuously to another part. Athetosis is a continuous stream of slow, flowing, writhi...
Huntington's Disease
Aug 1, 2007
Huntington's disease (Huntington's chorea) is a hereditary disease that begins with occasional involuntary jerking or spasms, then progresses to more pronounced involuntary movements (chorea and athetosis), mental deterioration, and death.
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Dystonia
Aug 1, 2007
Dystonia is characterized by involuntary sustained muscle contractions that may make people freeze in the middle of an action or make the entire body, the trunk, or another part of the body twist or turn.
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Coordination Disorders
Aug 1, 2007
Coordination disorders result from malfunction of the cerebellum, the part of the brain that coordinates voluntary movements.
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Fragile X–Associated Tremor/Ataxia Syndrome
Aug 1, 2007
Fragile X–associated tremor/ataxia syndrome is a genetic disorder that affects mostly men and causes tremor, loss of coordination, and dementia.
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Overview of Spinal Cord Disorders
Aug 1, 2007
The spinal cord is the main pathway of communication between the brain and the rest of the body. It is a long, fragile, tubelike structure that extends downward from the base of the brain. The cord is protected by the back bones (vertebrae) of the sp...
Injuries of the Spinal Cord and Vertebrae
Aug 1, 2007
Injuries may affect the spinal cord or the roots of the spinal nerves, which pass through the spaces between the back bones (vertebrae) of the spine. The bundle of nerves that extend downward from the spinal cord (cauda equina) may also be injured. I...
Compression of the Spinal Cord
Aug 1, 2007
Injuries and disorders can put pressure on the spinal cord, causing back pain, tingling, muscle weakness, and other symptoms.
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Cervical Spondylosis
Aug 1, 2007
Cervical spondylosis is degeneration of the disks and vertebrae in the neck, putting pressure on (compressing) the spinal cord in the neck.
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Syrinx
Aug 1, 2007
A syrinx is a fluid-filled cavity that develops in the spinal cord (called a syringomyelia), in the brain stem (called a syringobulbia), or in both.
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Hereditary Spastic Paraparesis
Aug 1, 2007
Hereditary spastic paraparesis is a rare hereditary disorder that causes gradual weakness with muscle spasms (spastic weakness) in the legs.
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Acute Transverse Myelitis
Aug 1, 2007
Acute transverse myelitis is inflammation that affects the spinal cord across its entire width (transversely) and thus blocks transmission of nerve impulses traveling up or down the spinal cord.
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Blockage of the Spinal Cord's Blood Supply
Aug 1, 2007
Blockage of an artery carrying blood to the spinal cord prevents the cord from getting blood and thus oxygen. As a result, tissues can die (called infarction).
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Subacute Combined Degeneration
Aug 1, 2007
Subacute combined degeneration is progressive degeneration of the spinal cord due to vitamin B12 deficiency.
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Tropical Spastic Paraparesis/HTLV-1–Associated Myelopathy
Aug 1, 2007
Tropical spastic paraparesis/HTLV-1–associated myelopathy is a slowly progressive disorder of the spinal cord caused by the human T-lymphotrophic virus 1 (HTLV-1).
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Overview of Anxiety Disorders
Aug 1, 2007
Anxiety disorders involve a state of distressing chronic but fluctuating nervousness that is inappropriately severe for the person's circumstances.
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Generalized Anxiety Disorder
Aug 1, 2007
Generalized anxiety disorder consists of excessive, usually daily, nervousness and worry (lasting 6 months or longer) about many activities or events.
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Anxiety Induced by Physical Disorders or Drugs
Aug 1, 2007
Anxiety can be caused by a physical disorder or the use or discontinuation of a drug. Physical disorders that can cause anxiety include the following:...
Panic Attacks and Panic Disorder
Aug 1, 2007
Panic is acute, short-lived, extreme anxiety with accompanying physical symptoms.
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Phobic Disorders
Aug 1, 2007
Phobias involve persistent, unrealistic, intense anxiety about and fear of certain situations, circumstances, or objects.
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Obsessive-Compulsive Disorder (OCD)
Aug 1, 2007
Obsessive-compulsive disorder is characterized by recurring, unwanted, anxiety-provoking, intrusive ideas, images, or impulses (obsessions) that may even seem silly, weird, nasty, or horrible to the person experiencing them. The person also ...
Posttraumatic Stress Disorder (PTSD)
Aug 1, 2007
Posttraumatic stress disorder (PTSD) is characterized by recurrent, intrusive recollections of an overwhelming traumatic event.
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Acute Stress Disorder
Aug 1, 2007
Acute stress disorder is a brief period of intrusive recollections occurring shortly after an overwhelming traumatic event. It is similar to posttraumatic stress disorder, except that it begins within 4 weeks of the traumatic event and lasts...
Overview of Pancreatitis
Aug 1, 2007
Pancreatitis is inflammation of the pancreas.
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Acute Pancreatitis
Aug 1, 2007
Acute pancreatitis is sudden inflammation of the pancreas that may be mild or life threatening but usually subsides.
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Chronic Pancreatitis
Aug 1, 2007
Chronic pancreatitis is long-standing inflammation of the pancreas that results in irreversible deterioration of pancreatic structure and function.
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Undernutrition
Aug 1, 2007
Undernutrition is a deficiency of calories or of one or more essential nutrients.
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Overview of Vitamins
Aug 1, 2007
Vitamins are a vital part of a healthy diet. The recommended dietary allowance (RDA)—the amount most healthy people need each day to remain healthy—has been determined for most vitamins. A safe upper limit (tolerable upper intake level) has ...
Folate
Aug 1, 2007
Folate (folic acid), with vitamin B12, is necessary for the formation of normal red blood cells and the synthesis of DNA (deoxyribonucleic acid), which is the genetic material of cells. Folate is also necessary for normal development of a fetus's ner...
Niacin
Aug 1, 2007
Niacin (nicotinic acid) is essential for the metabolism of carbohydrates, fats, and many other substances in the body. Foods rich in tryptophan (an amino acid), such as dairy products, can compensate for not consuming enough niacin in the diet becaus...
Riboflavin
Aug 1, 2007
Riboflavin (vitamin B2) is essential for the metabolism of carbohydrates (to produce energy) and amino acids. It also helps keep mucous membranes (such as those lining the mouth) healthy. Riboflavin is not toxic....
Thiamin
Aug 1, 2007
Thiamin (vitamin B1) is widely available in the diet. It is essential for the metabolism of carbohydrates (to produce energy) and for normal nerve and heart function. Thiamin is not toxic....
Vitamin A
Aug 1, 2007
Vitamin A (retinol) is necessary for the function of light-sensitive nerve cells (photoreceptors) in the eye's retina. It also helps keep the skin and the lining of the lungs, intestine, and urinary tract healthy and protects against infecti...
Vitamin B6
Aug 1, 2007
Vitamin B6 (pyridoxine) is essential for the metabolism of carbohydrates, amino acids, and fats (lipids), as well as for normal nerve function and for the formation of red blood cells. It also helps keep the skin healthy....
Vitamin B12
Aug 1, 2007
Vitamin B12 (cobalamins), with folate, is necessary for the formation and maturation of red blood cells and the synthesis of DNA (deoxyribonucleic acid), which is the genetic material of cells. Vitamin B12 is also necessary for normal nerve function....
Vitamin C
Aug 1, 2007
Vitamin C (ascorbic acid) is essential for the formation, growth, and repair of bone, skin, and connective tissue (which binds other tissues and organs together and includes tendons, ligaments, and blood vessels). Vitamin C helps maintain healthy tee...
Vitamin D
Aug 1, 2007
Two forms of vitamin D are important for nutrition:...
Vitamin E
Aug 1, 2007
Vitamin E (tocopherol) is an antioxidant: It protects cells against damage by free radicals, which are by-products of normal cell activity that participate in chemical reactions. Some of these reactions can be harmful. Many people take vitamin E supp...
Vitamin K
Aug 1, 2007
Vitamin K has two forms:...
Overview of Urinary Tract Obstruction
Aug 1, 2007
An obstruction anywhere along the urinary tract—from the kidneys, where urine is produced, to the urethra, through which urine leaves the body—can increase pressure inside the urinary tract and slow the flow of urine. An obstruction may occur suddenl...
Hydronephrosis
Aug 1, 2007
Hydronephrosis is distention (dilation) of the kidney with urine, caused by backward pressure on the kidney when the flow of urine is obstructed.
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Stones in the Urinary Tract
Aug 1, 2007
Stones (calculi) are hard masses that form anywhere in the urinary tract and may cause pain, bleeding, obstruction of the flow of urine, or an infection.
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Prevention of Cancer
Aug 1, 2007
Reducing the risk of certain cancers may be possible through dietary (see ) and other lifestyle changes. How risk can be reduced depends on the specific cancer. Tobacco use is directly associated with one third of all cancers. Not s...
Cancer Treatment Principles
Aug 1, 2007
Treating cancer is one of the most complex aspects of medical care. It involves a team that encompasses many types of doctors working together (for example, primary care doctors, gynecologists, medical oncologists, surgeons, radiotherapists, and path...
Surgery for Cancer
Aug 1, 2007
Surgery is a traditional form of cancer treatment. It is the most effective in eliminating most types of cancer before it has spread to lymph nodes or distant sites (metastasized). Surgery may be used alone or in combination with other treatments, su...
Radiation Therapy
Aug 1, 2007
Radiation is a form of intense energy generated by a radioactive substance, such as cobalt, or by specialized equipment, such as an atomic particle (linear) accelerator....
Chemotherapy
Aug 1, 2007
Chemotherapy involves the use of drugs to destroy cancer cells. Although an ideal drug would destroy cancer cells without harming normal cells, most drugs are not that selective. Instead, drugs are designed to inflict greater damage on cancer cells t...
Immunotherapy for Cancer
Aug 1, 2007
Immunotherapy is used to stimulate the body's immune system against cancer. For example, vaccines composed of antigens derived from tumor cells can boost the body's production of antibodies or immune cells (T lymphocytes). Extracts of weakened tuberc...
Combination Cancer Therapy
Aug 1, 2007
Chemotherapy drugs are most effective when given in combination (combination chemotherapy). The rationale for combination chemotherapy is to use drugs that work by different mechanisms of action, thereby decreasing the likelihood that resistant cance...
Alternative Medicine for Cancer
Aug 1, 2007
Some people turn to alternative medicine, including certain medicinal herbs (see ), to treat their cancer, instead of or in addition to standard treatment. However, most types of alternative medicine have not been subjected to careful scientific stud...
Diet and Cancer
Aug 1, 2007
Many studies have tried to determine whether eating specific foods increases or decreases a person's risk of getting cancer. Unfortunately, different studies sometimes have conflicting results, so it is hard to know what effect foods or dietary suppl...
Overview of Sunlight and Skin Damage
Aug 1, 2007
The skin shields the rest of the body from the sun's rays....
Sunburn
Aug 1, 2007
Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. The amount of sun exposure required to produce a burn varies with each person's pigmentation and ability to produce more melanin....
Photosensitivity Reactions
Aug 1, 2007
Photosensitivity, sometimes referred to as a sun allergy, is an immune system reaction that is triggered by sunlight. Photosensitivity reactions include solar urticaria, chemical photosensitization, and polymorphous light eruption and are usually cha...
Overview of Nail Disorders
Aug 1, 2007
The nail unit is made up of the nail plate and the surrounding structures. These structures include the nail bed, which underlies the nail and forms the attachment of the nail to the finger; the nail matrix, which is located at the base of the nail a...
Deformities and Discoloration of the Nails
Aug 1, 2007
About 50% of nail deformities are caused by a fungal infection (see ). The remainder result from various causes, including trauma, psoriasis, lichen planus, and occasionally cancer. Drugs, infections, and diseases can cause discoloration of the nails...
Fingernail and Toenail Infections
Aug 1, 2007
Infections may involve the nail itself, the bed under the nail, or the skin around the nail. Most nail infections are fungal (onychomycosis), but bacterial and viral infections can occur. Bacterial infections may occur in the cuticle or nail folds (p...
Ingrown Toenail
Aug 1, 2007
An ingrown toenail is a condition in which the edges of the nail grow into the surrounding skin.
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Fingernail and Toenail Trauma
Aug 1, 2007
Even minor trauma to the finger may cause changes in the nail. The nail may develop a small spot of white discoloration that starts at the injury location and grows up with the nail....
Tumors of the Nails
Aug 1, 2007
Benign and malignant tumors can affect the nail unit, causing a deformity. These tumors include noncancerous myxoid cysts, pyogenic granulomas, glomus tumors, Bowen's disease (an early form of skin cancer), squamous cell carcinoma, and malignant mela...
Structure of the Male Reproductive System
Aug 1, 2007
The penis consists of the root (which is attached to the abdominal wall), the body (the middle portion), and the glans penis (the cone-shaped end). The opening of the urethra (the channel that transports semen and urine) is located at the tip of the ...
Male Reproductive Function
Aug 1, 2007
During sexual activity, the penis becomes erect, enabling penetration during sexual intercourse. An erection results from a complex interaction of neurologic, vascular, hormonal, and psychologic actions. Pleasurable stimuli cause the brain to send ne...
Puberty in Boys
Aug 1, 2007
Puberty is the stage during which people reache full reproductive ability and develop the adult features of their gender. In boys, puberty usually occurs between the ages of 10 and 14 years. However, it is not unusual for puberty to begin as early as...
Effects of Aging on the Male Reproductive System
Aug 1, 2007
It is not clear whether aging itself or the disorders associated with aging cause the gradual changes that occur in men's sexual functioning. The frequency, duration, and rigidity of erections gradually decline throughout adulthood. Levels of the mal...
Contraception
Aug 1, 2007
Contraception is prevention of fertilization of an egg by a sperm (conception) or attachment of the fertilized egg to the lining of the uterus (implantation).
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Sterilization
Aug 1, 2007
Sterilization involves making a person incapable of reproduction.
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Abortion
Aug 1, 2007
Induced abortion is the intentional ending of a pregnancy by surgery or drugs.
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Basic First Aid Supplies
Aug 1, 2007
The medicine chest or first-aid kit should be kept well stocked. The following basic supplies are useful to have on hand:...
Emergency First Aid Priorities
Aug 1, 2007
The first priority is to assess a person's airway, breathing, and circulation (the ABCs). A problem in any of these areas is always fatal if not corrected. The airway (A)—the passage through which air travels to the lungs—can become blocked. Various ...
Cardiac Arrest
Aug 1, 2007
Cardiac arrest is what happens when a person dies. The heart does not beat and breathing ceases, which starves the body of oxygen. Sometimes a person can be revived during the first several minutes after cardiac arrest. However, the more tim...
Choking
Aug 1, 2007
Maneuvers to relieve choking are frequently life saving. Adults most often choke on a piece of food, such as a large piece of meat. Infants do not have well-developed swallowing reflexes and may choke if given small, rounded foods such as peanuts or ...
Internal Bleeding
Aug 1, 2007
Heavy internal bleeding may occur in the abdominal cavity, chest cavity, digestive tract, or tissues surrounding broken large bones, such as the thigh bone (femur) and pelvis....
Wounds
Aug 1, 2007
Cuts or tears in tissue (lacerations), scrapes (abrasions), and puncture wounds can be caused by bites (see ) or other injuries. Wounds that are not caused by bites and are not extensive usually heal rapidly without any problems. However, some wounds...
Soft Tissue Injuries
Aug 1, 2007
Soft tissue injuries include bumps and bruises (contusions) and small tears of muscles (minor strains) or of ligaments and tendons near joints (minor sprains)....
Severed or Constricted Limbs or Digits
Aug 1, 2007
Body parts such as fingers and toes can become severed. Also, tissue may die because blood flow has been cut off by rings or other constricting devices. Rings cut off blood flow when parts of the body near the ring swell, often as the result of an in...
Overview of Aging
Aug 1, 2007
Aging is a gradual, continuous process of spontaneous change that begins at birth and continues throughout all stages of life. It involves maturation and development for children, adolescents, and young adults. Then, during middle and late age, many ...
Changes in the Body With Aging
Aug 1, 2007
The body changes with aging because changes occur in individual cells and in whole organs. These changes result in changes in function and in appearance....
Disorders in Older People
Aug 1, 2007
Some disorders occur almost exclusively in older people. They are sometimes called geriatric syndromes (geriatric refers to the medical care of older people)....
Indirect Influences on Health in Older People
Aug 1, 2007
Circumstances that may seem unrelated to health can affect the health of older people....
Disorders of Accelerated Aging
Aug 1, 2007
Certain disorders have the some of the same effects as aging. Scientists study what happens in these disorders to try to learn what causes aging. For example, they identify the genes that are defective in these disorders and compare them with the sam...
Overview of Rehabilitation
Jul 1, 2007
Rehabilitation services are needed by people who have lost the ability to function normally, often because of trauma, a stroke, an infection, a tumor, surgery, or a progressive disorder (such as arthritis). A pulmonary rehabilitation program (see ) i...
Treatment of Pain and Inflammation
Jul 1, 2007
Therapists treat pain and inflammation. Such treatment makes movement easier and enables people to participate more fully in rehabilitation. Techniques used include heat therapy, cold therapy, electrical stimulation, traction, massage, and acupunctur...
Physical Therapy (PT)
Jul 1, 2007
Physical therapy involves exercising and manipulating the body. It can improve joint and muscle function, helping people stand, balance, walk, and climb stairs better. Techniques include range-of-motion exercises, muscle-strengthening exercises, coor...
Occupational Therapy (OT)
Jul 1, 2007
Occupational therapy is intended to enhance a person's ability to do basic self-care activities, useful work, and leisure activities. This therapy focuses on the coordination of many abilities required for even simple activities:...
Rehabilitation for Specific Problems
Jul 1, 2007
For many problems—for example, heart disorders, stroke, other brain injuries, spinal injuries, hip fractures, amputation, and loss of hearing, speech, or vision—specific rehabilitation programs are available. Rehabilitation is sometimes needed for ot...
Bones
Jul 1, 2007
Bone, although strong, is a constantly changing tissue that has several functions. Bones serve as rigid structures to the body and as shields to protect delicate internal organs. They provide housing for the bone marrow, where the blood cells are for...
Muscles
Jul 1, 2007
There are three types of muscles: skeletal, smooth, and cardiac (heart). Two of these kinds—skeletal and smooth—are part of the musculoskeletal system....
Tendons and Bursae
Jul 1, 2007
Tendons are tough bands of connective tissue made up mostly of a rigid protein called collagen. Tendons firmly attach each end of a muscle to a bone. They are often located within sheaths, which are lubricated to allow the tendons t...
Ligaments
Jul 1, 2007
Ligaments are tough fibrous cords composed of connective tissue that contains both collagen and elastic fibers. The elastic fibers allow the ligaments to stretch to some extent. Ligaments surround joints and bind them together. They help strengthen a...
Joints
Jul 1, 2007
Joints are the junction between two or more bones. Some joints do not normally move, such as those located between the plates of the skull. Other joints allow a large and complex range of motion. The configuration of a joint determines the degree and...
Effects of Aging on the Musculoskeletal System
Jul 1, 2007
From about age 30, the density of bones begins to diminish in men and women. This loss of bone density accelerates in women after menopause. As a result, bones become more fragile and are more likely to break (see ), especially in old age....
Overview of the Cranial Nerves
Jul 1, 2007
Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing, hearing, and taste), and others control muscles in th...
Internuclear Ophthalmoplegia
Jul 1, 2007
Internuclear ophthalmoplegia is impairment of horizontal eye movements caused by damage to certain connections between nerve centers in the brain stem.
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Conjugate Gaze Palsies
Jul 1, 2007
In conjugate gaze palsies, the two eyes cannot move in one direction (side to side, up, or down) at the same time.
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Palsies of Cranial Nerves That Control Eye Movement
Jul 1, 2007
These disorders involve paralysis of cranial nerves that control eye movement (the 3rd, 4th, or 6th nerves), impairing the ability to move the eyes. How eye movement is affected depends on which nerve is affected.
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Trigeminal Neuralgia
Jul 1, 2007
Trigeminal neuralgia (tic douloureux) is severe facial pain due to malfunction of the 5th cranial nerve (trigeminal nerve). This nerve carries sensory information from the face to the brain and controls the muscles involved in chewing.
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Bell's Palsy
Jul 1, 2007
Bell's palsy is sudden weakness or paralysis of muscles on one side of the face due to malfunction of the 7th cranial nerve (facial nerve). This nerve moves the facial muscles, stimulates the salivary and tear glands, and enables the front p...
Hemifacial Spasm
Jul 1, 2007
Hemifacial spasm is painless involuntary twitching of one side of the face due to malfunction of the 7th cranial nerve (facial nerve). This nerve moves the facial muscles, stimulates the salivary and tear glands, and enables the front part o...
Glossopharyngeal Neuralgia
Jul 1, 2007
Glossopharyngeal neuralgia consists of recurring attacks of severe pain in the back of the throat, the area near the tonsils, the back of the tongue, and part of the ear. The pain is due to malfunction of the 9th cranial nerve (glossopharyng...
Hypoglossal Nerve Disorders
Jul 1, 2007
Disorders of the 12th cranial nerve (hypoglossal nerve) cause weakness or wasting (atrophy) of the tongue on the affected side. This nerve moves the tongue.
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Overview of Blood Transfusion
Jul 1, 2007
A blood transfusion is the transfer of blood or a blood component from one person (a donor) to another (a recipient).
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Blood Donation Process
Jul 1, 2007
Donating blood is very safe. The entire process of donating whole blood (that is, blood with all component cells) takes about 1 hour. Blood donors must be at least 17 years old and weigh at least 110 pounds. In addition, they must be in good health: ...
Types of Transfusions
Jul 1, 2007
Most blood donations are divided (fractionated) into their components: red blood cells, platelets, clotting factors, plasma, antibodies (immunoglobulins), and white blood cells. Depending on the situation, people may receive only the cells from blood...
Special Blood Donation Procedures
Jul 1, 2007
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Precautions and Adverse Reactions During Blood Transfusion
Jul 1, 2007
To minimize the chance of an adverse reaction during a transfusion, health care practitioners take several precautions. Before starting the transfusion, usually a few hours or even a few days beforehand, a technician mixes a drop of the donor's blood...
Autoimmune Disorders
Jul 1, 2007
An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues.
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Overview of the Female Reproductive System
Jul 1, 2007
The female reproductive system consists of the external and internal genital organs. The breasts are sometimes considered part of the reproductive system (see ). However, other parts of the body also affect the development and functioning of the repr...
Female External Genital Organs
Jul 1, 2007
The external genital organs include the mons pubis, labia majora, labia minora, Bartholin's glands, and clitoris. The area containing these organs is called the vulva. The external genital organs have three main functions: ...
Female Internal Genital Organs
Jul 1, 2007
The internal genital organs form a pathway (the genital tract). This pathway consists of the following:...
Puberty in Girls
Jul 1, 2007
Puberty is a sequence of events in which physical changes occur, resulting in adult physical characteristics and capacity to reproduce. These physical changes are regulated by changes in the levels of hormones that are produced by the pituitary gland...
Menstrual Cycle
Jul 1, 2007
Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. It occurs in approximately monthly cycles throughout a woman's reproductive life, except during pregnancy. Menstruation starts during puberty (at menarche...
Effects of Aging on the Female Reproductive System
Jul 1, 2007
Around menopause (see ), changes in the genital organs occur rapidly. Menstrual cycles stop, and the ovaries stop producing estrogen. After menopause, the tissues of the labia minora, clitoris, vagina, and urethra thin (atrophy). This thinning can re...
Overview of Social Issues Affecting Children
Jul 1, 2007
To thrive, a child must experience the consistent and ongoing care by a loving, nurturing caregiver, whether that person is a parent or substitute caregiver. The security and support that such an adult can provide gives a child the self-confidence an...
Illness and Death in Infants
Jul 1, 2007
The medical needs of premature newborns or ill infants often require that they be separated from their parents temporarily. Although doctors may allow parents to hold their infant some of the time, medical care often sharply limits the opportunity fo...
Illness in Children
Jul 1, 2007
Severe illness, even if temporary, can provoke a great deal of anxiety for children and their families. Chronic problems, such as asthma, diabetes, hearing or vision impairments, and cerebral palsy, or disability usually cause even more emotional dis...
Divorce and Children
Jul 1, 2007
Separation and divorce, and the events leading up to them, interrupt the stability and predictability that children need. Other than the death of an immediate family member, divorce is the most stressful event that can affect a family. Because the wo...
Child Care
Jul 1, 2007
About 80% of children receive child care outside the home before they start school. Many children aged 5 to 12 also receive care outside the home before or after school. Sources of care include relatives, neighbors, licensed and unlicensed private ho...
Foster Care
Jul 1, 2007
Foster care is care provided for children whose families are temporarily unable to care for them. The local government determines the process of arranging foster care. Foster care is surprisingly common in the United States—about 750,000 children are...
Adoption
Jul 1, 2007
Adoption is the legal process of adding a person to an existing family. Adoption, unlike foster care, is meant to be permanent. The goal of adoption is to provide lifelong security to the child and the adoptive family....
Menopause
Jun 1, 2007
Menopause is the permanent end of menstrual periods and thus of fertility.
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Premature Menopause
Jun 1, 2007
Premature menopause (premature ovarian failure) is the permanent end of menstrual periods before age 40 because ovulation stops and the ovaries become unable to produce hormones.
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Overview of Urinary Tract Injury
Jun 1, 2007
The kidneys and the rest of the urinary tract may become injured in a number of ways. Examples include injuries from a blunt force (most commonly motor vehicle collisions, falls, or sports injuries) or a pentrating force (most commonly gunshot or sta...
Bladder Injuries
Jun 1, 2007
A bladder injury often occurs when the pelvis is injured, as in a high-speed motor vehicle collision or a fall. Penetrating wounds, usually from gunshots, also can injure the bladder. In addition, a bladder injury may occur unintentionally during sur...
Kidney Injuries
Jun 1, 2007
The kidney is injured more often than any of the organs along the urinary tract. Blunt force due to motor vehicle collisions, falls, or sports injuries is the usual cause of injury. Penetrating kidney injuries can result from gunshot or stab wounds. ...
Ureteral Injuries
Jun 1, 2007
Most injuries to the ureter occur during pelvic or abdominal operations, such as removal of the uterus (hysterectomy) or the colon (colectomy) or repair of an abdominal aortic aneurysm, or during ureteroscopy (an examination of the ureter with a rigi...
Urethral Injuries
Jun 1, 2007
Most urethral injuries occur in men. Common causes include pelvic fractures and straddle injuries (injuries to the area between the legs). The urethra can also be injured unintentionally during surgical procedures performed directly on the urethra or...
Information Sources for Medical Decisions
Jun 1, 2007
Most doctors rely on their education and experience: what they have learned from their training, from their colleagues, and from diagnosing and treating people with similar problems. Doctors also read medical books and journals, consult with...
Medical Testing Decisions
Jun 1, 2007
Tests are done to screen for disease, diagnose disease, classify and measure the severity or stage of disease, and monitor the course of a disease, especially its response to treatment....
Treatment Decisions
Jun 1, 2007
Before recommending a course of action, doctors weigh the potential risk of harm from a treatment against its potential benefit. ...
Participating in Decision Making
Jun 1, 2007
To participate fully in the medical decision making process, people need to work closely with their doctors. People may wish to obtain additional information about a recommended test or treatment before making a decision (see ). Information can be ob...
Realities of Decision Making
Jun 1, 2007
Whenever a decision must be made about diagnosis or treatment, two tasks must be accomplished. The first is to choose information resources that are most appropriate to help determine the best course of action. The second is to apply what is learned ...
Introduction
May 1, 2007
Gone are the days when people can rely solely on their family doctor with the help of a nurse to take charge of their health care. To obtain the best health care today, people must participate actively in the process. Active participation means many ...
The Primary Care Doctor
May 1, 2007
Typically, the entry point into the health care system is a primary care practitioner, usually a doctor but sometimes a nurse practitioner or physician's assistant. Having a primary care doctor has many advantages that can lead to better care. People...
When to See a Doctor
May 1, 2007
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Making the Most of a Health Care Visit
May 1, 2007
Preparing for a health care visit helps people get the most out of time spent with a doctor or another health care practitioner. Preparing ahead also helps people communicate with a practitioner more effectively. Information and questions for the pra...
Getting a Second Opinion
May 1, 2007
Despite many similarities in training, doctors may vary in their opinions about how to diagnose or treat certain disorders. Such differences can occur among the best of doctors. Differences often occur because the evidence for benefits and risks is n...
Handling Medical Records
May 1, 2007
People may not have total access to their medical record kept in the doctor's office. But usually the person owns the medical information, and the doctor or institution owns the document itself. The courts can require submission of copies or summarie...
Researching a Disorder
May 1, 2007
When a disorder is first diagnosed, the doctor often gives a handout that summarizes key points of information. People may also have some general knowledge of the disorder from newspaper or magazine articles or television or radio shows....
How Health Care Is Paid For
May 1, 2007
Health care, particularly hospitalization, advanced technologies, and complicated treatments, is so expensive that most people cannot afford to pay for it by themselves. Total health care costs annually in the United States were about $1.9 trillion i...
Overview of Drugs
May 1, 2007
A drug is defined by U.S. law as any substance (other than a food or device) intended for use in the diagnosis, cure, relief, treatment, or prevention of disease or intended to affect the structure or function of the body. (Oral contraceptives are an...
Drug Design and Development
May 1, 2007
Many of the drugs in current use were discovered by experiments conducted in animals and humans. However, many drugs are now being designed with the specific disorder in view. Abnormal biochemical and cellular changes caused by disease are identified...
Placebos
May 1, 2007
Placebos are substances that are made to resemble drugs but do not contain an active drug.
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Drug Effectiveness and Safety
May 1, 2007
The main goals of drug development are effectiveness (efficacy) and safety. Because all drugs can harm as well as help, safety is relative. The difference between the usual effective dose and the dose that produces severe or life-threatening side eff...
Adherence to Drug Treatment
May 1, 2007
Adherence is the degree to which a person takes prescribed drugs as directed.
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Overview of Low Blood Pressure
May 1, 2007
Low blood pressure (hypotension) is blood pressure low enough to cause symptoms such as dizziness and fainting.
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Fainting
May 1, 2007
Fainting (syncope) is a sudden, brief loss of consciousness.
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Orthostatic Hypotension
May 1, 2007
Orthostatic hypotension is an excessive decrease in blood pressure that occurs when a person stands up, resulting in reduced blood flow to the brain and dizziness or fainting.
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Postprandial Hypotension
May 1, 2007
Postprandial hypotension is an excessive decrease in blood pressure that occurs after a meal.
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Overview of Pulmonary Rehabilitation
May 1, 2007
Pulmonary rehabilitation is a program designed for people who have chronic lung disease. Its primary goal is to enable people to achieve and maintain their maximum level of independence and functioning. Although most pulmonary rehabilitation programs...
Oxygen Therapy
May 1, 2007
Some people with chronic lung disease need only a brief period of oxygen therapy during an acute exacerbation of their lung disease. Others, in whom oxygen levels in the blood are consistently low, may require oxygen therapy on a daily basis. In thes...
Chest Physical Therapy
May 1, 2007
Respiratory therapists use several different techniques to help treat lung disease, including postural drainage, suctioning, and breathing exercises. The choice of therapy is based on the underlying disease and the person's overall condition....
Introduction
May 1, 2007
Mental health (psychiatric or psychologic) disorders involve disturbances in thinking, emotion, or behavior. Small disturbances in these aspects of life are common, but when such disturbances interfere with daily life, they are considered mental illn...
Mental Illness in Society
May 1, 2007
About 30 to 50% of adults will experience a mental illness at some point in their lives. More than 50% of these people experience moderate to severe symptoms. In fact, 4 of the 10 leading causes of disability among people aged 5 and older are mental ...
Classification and Diagnosis of Mental Illness
May 1, 2007
In 1952, the American Psychiatric Association first published the Diagnostic and Statistical Manual of Mental Disorders (DSM-I), marking the first attempt to approach the diagnosis of mental illness through standardized definitions and criteria. The ...
Treatment of Mental Illness
May 1, 2007
Extraordinary advances have been made in the treatment of mental illness. Understanding what causes some mental health disorders helps doctors tailor treatment to those disorders. As a result, many mental health disorders can now be treated nearly as...
Symptoms
May 1, 2007
Some symptoms, such as diarrhea, constipation, bleeding from the digestive tract, regurgitation, and difficulty swallowing, usually suggest a digestive disorder. More general symptoms, such as abdominal pain, flatulence, loss of appetite, and nausea,...
Diagnosis
May 1, 2007
Usually, a doctor can determine whether a person has a digestive disorder based on a medical history and a physical examination. The doctor can then select appropriate procedures that help to confirm the diagnosis, determine the extent and severity o...
Irritable Bowel Syndrome (IBS)
May 1, 2007
Irritable bowel syndrome (IBS) is a disorder of the entire digestive tract that causes abdominal pain and constipation or diarrhea.
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Overview of Hepatitis
May 1, 2007
Hepatitis is inflammation of the liver.
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Acute Viral Hepatitis
May 1, 2007
Acute viral hepatitis is inflammation of the liver caused by infection with one of the five hepatitis viruses. In most people, the inflammation begins suddenly and lasts only a few weeks.
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Chronic Hepatitis
May 1, 2007
Chronic hepatitis is inflammation of the liver that lasts at least 6 months.
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Endometriosis
May 1, 2007
Endometriosis is a noncancerous disorder in which patches of endometrial tissue—normally occurring only in the lining of the uterus (endometrium)—appear outside the uterus.
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Drug Use During Pregnancy
May 1, 2007
More than 90% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy. In general, drugs should not be used during pregnancy unle...
Overview of Viral Infections in Children
May 1, 2007
Viral infections are common among people of all ages but often seem to be concentrated in infants and children. Most childhood viral infections are not serious and include such diverse illnesses as colds with a sore throat, vomiting and diarrhea, and...
Viral Central Nervous System Infections in Children
May 1, 2007
Central nervous system infections are extremely serious. Meningitis affects the membranes surrounding the brain and spinal cord. Encephalitis affects the brain itself.
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Chickenpox
May 1, 2007
Chickenpox (varicella) is a highly contagious infection with the varicella-zoster virus that causes a characteristic itchy rash, consisting of small, raised, blistered, or crusted spots.
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Erythema Infectiosum
May 1, 2007
Erythema infectiosum (fifth disease, parvovirus B19 infection) is a contagious viral infection that causes a blotchy or raised red rash with mild illness.
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Human Immunodeficiency Virus (HIV) Infection in Children
May 1, 2007
Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and causes acquired immunodeficiency syndrome (AIDS).
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Measles
May 1, 2007
Measles (rubeola, 9-day measles) is a highly contagious viral infection that causes various symptoms and a characteristic rash.
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Mumps
May 1, 2007
Mumps (epidemic parotitis) is a contagious viral infection that causes painful enlargement of the salivary glands. The infection may also affect the testes, brain, and pancreas, especially in adults.
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Polio
May 1, 2007
Polio (poliomyelitis, infantile paralysis) is a highly contagious, sometimes fatal, viral infection that affects nerves and can cause permanent muscle weakness, paralysis, and other symptoms.
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Respiratory Tract Infections in Children
May 1, 2007
Respiratory tract infections affect the nose, throat, and airways and may be caused by any of several different viruses.
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Roseola Infantum
May 1, 2007
Roseola infantum (exanthem subitum, pseudorubella) is a viral infection of infants or very young children that causes a high fever followed by a rash.
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Rotavirus Infection
May 1, 2007
Rotavirus is a common and contagious virus that causes vomiting and diarrhea.
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Rubella
May 1, 2007
Rubella (German measles, 3-day measles) is a contagious viral infection that causes mild symptoms, such as joint pain and a rash.
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Subacute Sclerosing Panencephalitis (SSPE)
May 1, 2007
Subacute sclerosing panencephalitis, a progressive and usually fatal disorder, is a rare complication of measles that appears months or years later and causes mental deterioration, muscle jerks, and seizures.
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Juvenile Idiopathic Arthritis (JIA)
May 1, 2007
Juvenile idiopathic arthritis is persistent or recurring inflammation of the joints similar to rheumatoid arthritis (see ) but beginning at or before age 16.
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Overview of Eye Injuries
May 1, 2007
The structure of the face and eyes is well suited for protecting the eyes from injury. The eyeball is set into the orbit, a socket surrounded by a strong, bony ridge. The eyelids close quickly to form a barrier to foreign objects, and the eye can tol...
Blunt Injuries to the Eye
May 1, 2007
A blunt impact may damage the structures at the front of the eye (the eyelid, conjunctiva, sclera, cornea, iris, and lens) and those at the back of the eye (retina and optic nerve). Such an impact may also break (fracture) the bones that surround the...
Fractures of the Orbit
May 1, 2007
A severe blow to the face can fracture any of several bones that form the orbit. Occasionally, the eyeball itself also is damaged....
Lacerated Eyeball
May 1, 2007
Most cuts (lacerations) around the eyes affect the eyelids rather than the eyeball. Of those that affect the eyeball, many are superficial and minor. However, some cuts go through the white of the eye (sclera) or the transparent dome on the front sur...
Eyelid Lacerations
May 1, 2007
If the skin around the eye or on the eyelid has been cut, stitches may be needed. When possible, stitches near the edge of the eyelid should be placed by an ophthalmologist (a medical doctor who specializes in eye disorders) to ensure that no deformi...
Corneal Abrasions and Foreign Bodies
May 1, 2007
The most common eye injuries involve the surface of the transparent dome on the front surface of the eye (cornea). They include scratches (abrasions) and foreign bodies (objects). Foreign bodies in the cornea leave abrasions behind after they are rem...
Chemical Burns to the Eye
May 1, 2007
The eyelids close quickly in a reflex reaction to protect the eyes from harm. However, irritating or harmful chemicals still sometimes get onto the surface of the eye, causing burns. The most dangerous chemical burns involve strong acids or alkali. A...
Traumatic Iritis and Chemical Iritis
May 1, 2007
Iritis (also known as iridocyclitis or uveitis) is inflammation of the pigmented inside lining of the eye (uvea), iris, or both.
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Overview of Limb Prosthetics
May 1, 2007
A prosthesis is an artificial device that replaces a missing body part.
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Prosthetic Parts and Options
May 1, 2007
A limb prosthesis has three main parts: the interface, the components, and the cover....
Preparing to Use a Prosthesis
May 1, 2007
Before surgery, a surgeon, prosthetist, and physical therapist discuss plans and goals with the person who requires amputation. Also before surgery, everyone who requires an amputation should, if possible, discuss what happens after surgery with a pe...
Fitting the Prosthesis
May 1, 2007
A prosthetist custom designs the interface (socket and frame), then constructs it by hand. The fit of the interface, particularly the socket, is crucial to success—much more so than the type of prosthesis, including the components. If the interface f...
Skin Care for Amputees
May 1, 2007
Skin that comes in contact with the prosthesis must be cared for meticulously to prevent skin damage such as irritation, skin breakdown, and infection. Skin breakdown is the process of skin being worn away, possibly resulting in sores....
Stump Swelling
May 1, 2007
The stump tends to swell when the liner is not worn, as occurs during sleep. Consequently, people may have difficulty putting the prosthesis on after they wake up. Wearing a shrinker (an elastic sock used to control swelling) or an elastic bandage wh...
Loss of Suction
May 1, 2007
Sometimes a prosthesis becomes loose while it is being worn. The cause may be malfunction of part of the prosthesis. The one-way valve on the socket (used to form a tight seal) may leak, breaking the seal required to keep the prosthesis on. Or other ...
Stump Pain
May 1, 2007
Many people experience phantom pain at some time. The phantom aspect is not the pain, which is real, but the location of the pain—a limb that has been amputated. Phantom pain is more likely if the pain before amputation was severe or lasted a long ti...
Overview of Response to Drugs
Apr 1, 2007
Everyone responds to drugs differently. The way a person responds to a drug is affected by many factors, including genetic makeup, age, body size, the use of other drugs and dietary supplements (such as medicinal herbs—see ), the consumption of food ...
Genetic Makeup and Response to Drugs
Apr 1, 2007
Differences in genetic (inherited) makeup among individuals affect what the body does to a drug and what the drug does to the body. The study of genetic differences in the response to drugs is called pharmacogenetics....
Drug Interactions
Apr 1, 2007
The effect a drug has on a person may be different than expected because that drug interacts with...
Tolerance and Resistance to Drugs
Apr 1, 2007
Tolerance is a person's diminished response to a drug, which occurs when the drug is used repeatedly and the body adapts to the continued presence of the drug. Resistance refers to the ability of microorganis...
Overview of Generic Drugs and Drug Naming
Apr 1, 2007
Drugs often have several names. When a drug is first discovered, it is given a chemical name, which describes the atomic or molecular structure of the drug. The chemical name is thus usually too complex and cumbersome for general use. Next, ...
Bioequivalence and Interchangeability of Generic Drugs
Apr 1, 2007
When a company develops a generic version of a trade-name drug, the company's experts in drug formulation must figure out how to make it. It is not enough for them to simply reproduce the trade-name drug's chemical structure or to buy the active ingr...
Generic Biologic Drugs
Apr 1, 2007
Traditional drugs are called small-molecule agents because the active ingredient is usually a single, discrete chemical entity. Biologic drugs are complex products that can be derived from viruses, blood and body tissues, antibodies, toxins and antit...
Overview of Over-the-Counter Drugs
Apr 1, 2007
Over-the-counter (OTC) drugs are those available without a prescription.
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Precautions With Over-the-Counter Drugs
Apr 1, 2007
Certain groups of people, such as the very young, the very old, the very sick, and pregnant and breastfeeding women, are more vulnerable to harm from drugs, including OTC drugs. When such people use drugs, special precautions, which may include a doc...
High Blood Pressure
Apr 1, 2007
High blood pressure (hypertension) is abnormally high pressure in the arteries.
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Hearing Loss and Deafness
Apr 1, 2007
Hearing loss is deterioration in hearing. Deafness is profound hearing loss.
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Diabetes Mellitus in Children(DM)
Apr 1, 2007
Diabetes mellitus is a disorder in which blood sugar (glucose) levels are abnormally high because the body does not produce enough insulin.
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Shock
Mar 1, 2007
Shock is a life-threatening condition in which blood pressure is too low to sustain life.
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Overview of Urinary Tract Symptoms
Mar 1, 2007
Kidney and urinary tract disorders can affect one or both kidneys, one or both ureters, the bladder, or the urethra....
Burning or Pain with Urination
Mar 1, 2007
Burning or pain with urination (dysuria) may be felt at the opening to the urethra or, less often, over the bladder (in the pelvis, the lower part of the abdomen just above the pubic bone). Occasionally, if a woman has vaginal irritation (for example...
Flank pain
Mar 1, 2007
Pain caused by kidney disorders usually is felt in the side (flank) or small of the back. Occasionally, the pain radiates to the center of the abdomen. Usually pain occurs because the kidney's outer covering (renal capsule) is stretched by a...
Increased Urination
Mar 1, 2007
Most people urinate about 4 to 6 times a day, mostly in the daytime. Normally, adults pass between 3 cups (700 milliliters) and 2 quarts (2 liters) of urine a day. Infants may pass as little as 1 cup (230 milliliters) per day. Urination can be increa...
Swelling
Mar 1, 2007
Swelling results from accumulation of fluid in the tissues (edema). The swelling may cause weight gain. Swelling is usually most noticeable in the ankles and feet, but it may also involve the abdomen, lower back, hands, and face. If swelling is parti...
Urinating at Night
Mar 1, 2007
Needing to urinate during the night (nocturia) is more common among older people. It can contribute to sleep problems and to falls, especially if a person is rushing to the bathroom or if the area is not well lit. ...
Hesitating, Straining, and Dribbling
Mar 1, 2007
A hesitating start when urinating, a need to strain, a weak and trickling stream of urine, and dribbling at the end of urination are common symptoms of a partially obstructed urethra. In men, these symptoms are caused most commonly by an enlarged pro...
Urgency
Mar 1, 2007
A compelling need to urinate (urgency), which may feel like almost constant painful straining (tenesmus), can be caused by bladder irritation. Incontinence may occur if a person does not urinate immediately. Urgency may be caused by a bladder infecti...
Blood in the Urine
Mar 1, 2007
Blood in the urine (hematuria) can make the urine appear red or brown, depending on the amount of blood, how long it has been in the urine, and how acidic the urine is. An amount of blood too small to turn the urine red may be detected by chemical te...
Gas in the Urine
Mar 1, 2007
Passing gas (air) in the urine, a rare symptom, usually indicates an abnormal connection (fistula) between the urinary tract and the intestine, which normally contains gas. A fistula may be a complication of divert...
Changes in the Urine's Color
Mar 1, 2007
Normally, dilute urine is nearly colorless. Concentrated urine is deep yellow. Colors other than yellow are abnormal....
Changes in the Urine's Odor
Mar 1, 2007
The odor of urine can vary and does not usually indicate a disorder except in people who have certain rare metabolic disorders....
Tests for Kidney and Urinary Tract Disorders
Mar 1, 2007
Doctors sometimes need to do tests or procedures to diagnose a kidney or urinary tract disorder....
Overview of Kidney Filtering Disorders
Mar 1, 2007
Each kidney contains about 1 million filtering units (glomeruli). The glomeruli are made up of many microscopic clusters of tiny blood vessels (capillaries) with small pores. These blood vessels are designed to leak fluid from the bloodstrea...
Glomerulonephritis (Nephritic Syndrome)
Mar 1, 2007
Glomerulonephritis (nephritic syndrome) is a disorder of glomeruli (clusters of microscopic blood vessels in the kidneys with small pores through which blood is filtered). It is characterized by body tissue swelling (edema), high blood press...
Nephrotic Syndrome
Mar 1, 2007
Nephrotic syndrome is a disorder of the glomeruli (clusters of microscopic blood vessels in the kidneys that have small pores through which blood is filtered) in which excessive amounts of protein are excreted in the urine. This typically le...
Tubulointerstitial Nephritis
Mar 1, 2007
Tubulointerstitial nephritis is inflammation that affects the tubules of the kidneys and the tissues that surround them (interstitial tissue).
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Overview of Parasitic Infections
Mar 1, 2007
A parasite is an organism that lives on or inside another organism (the host) and harms the host....
Amebiasis
Mar 1, 2007
Amebiasis is an infection of the large intestine and sometimes the liver and other organs that is caused by the single-celled protozoan parasite Entamoeba histolytica, an ameba. Amebiasis may cause diarrhea, cramping abdominal pain, pain ove...
Amebic Infections Due to Free-Living Amebas
Mar 1, 2007
Free-living amebas are protozoa that live in soil or water and do not need to live in people or animals. Although they rarely cause human infection, certain types of these amebas can cause serious, life-threatening diseases. The most common diseases ...
Ascariasis
Mar 1, 2007
Ascariasis is infection caused by Ascaris lumbricoides, an intestinal roundworm. The infection often causes no symptoms but may cause fever, coughing, and wheezing, followed by abdominal cramps. In severe infections, children may not grow no...
Babesiosis
Mar 1, 2007
Babesiosis is infection of red blood cells caused by the single-celled protozoan parasite Babesia. The infection may cause fever, headache, body aches, and fatigue.
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Cryptosporidiosis
Mar 1, 2007
Cryptosporidiosis is an intestinal infection caused by Cryptosporidium, a protozoan. The main symptoms are abdominal cramping and diarrhea.
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Dracunculiasis
Mar 1, 2007
Dracunculiasis is infection caused by the roundworm Dracunculus medinensis. It causes a painful, inflamed skin sore and debilitating arthritis.
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Giardiasis
Mar 1, 2007
Giardiasis is an infection of the small intestine caused by the single-celled protozoan parasite Giardia lamblia. The main symptoms are abdominal cramping and diarrhea.
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Hookworm Infection
Mar 1, 2007
Hookworm infection (ancylostomiasis) is an infection of the intestines that can cause an itchy rash, respiratory and gastrointestinal problems, and eventually chronic blood loss and iron deficiency anemia.
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Leishmaniasis
Mar 1, 2007
Leishmaniasis is caused by several species of Leishmania protozoa. Leishmaniasis includes disorders that affect internal organs and those that affect the skin and sometimes mucous membranes of the nose and mouth, causing bumps or sores.
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Malaria
Mar 1, 2007
Malaria is infection of red blood cells with one of four species of Plasmodium, a protozoan. Malaria causes fever, chills, sweating, an enlarged spleen, and anemia (due to the breakdown of infected red blood cells).
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Microsporidiosis
Mar 1, 2007
Microsporidiosis is infection caused by Microsporidia protozoa. It causes diarrhea and eye symptoms.
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Onchocerciasis
Mar 1, 2007
Onchocerciasis (river blindness) is infection with the roundworm Onchocerca volvulus. It causes itching, a rash, sometimes with scarring, as well as eye symptoms that may lead to blindness.
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Pinworm Infection
Mar 1, 2007
Pinworm infection (enterobiasis) is caused by the intestinal roundworm Enterobius vermicularis and usually affects children.
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Schistosomiasis
Mar 1, 2007
Schistosomiasis (bilharziasis) is infection caused by flatworms (flukes), called schistosomes.
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Tapeworm Infection
Mar 1, 2007
Tapeworm infection of the intestine occurs when people eat raw, contaminated pork, beef, or freshwater fish.
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Toxocariasis
Mar 1, 2007
Toxocariasis (visceral larva migrans) is infection caused by larvae of the roundworms Toxocara canis or Toxocara cati.
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Toxoplasmosis
Mar 1, 2007
Toxoplasmosis is infection caused by the single-celled protozoan parasite Toxoplasma gondii. Symptoms may include swollen lymph nodes, fever, a vague ill feeling, and sometimes a sore throat, blurred vision, and eye pain.
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Trichinosis
Mar 1, 2007
Trichinosis is infection caused by the roundworm Trichinella spiralis. Symptoms include diarrhea, abdominal cramps, muscle pain, and fever.
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Whipworm Infection
Mar 1, 2007
Whipworm infection (trichuriasis) is an intestinal infection caused by the roundworm Trichuris trichiura.
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Routine Gynecologic Care
Mar 1, 2007
Preventive health care includes having regular gynecologic examinations, even when no symptoms are present, and screening tests. Screening tests are done before people have any symptoms to check for disorders that can be prevented or treated effectiv...
Gynecologic History and Physical Examination
Mar 1, 2007
During a visit for gynecologic care, doctors ask questions and do a physical examination....
Tests for Gynecologic Disorders
Mar 1, 2007
Sometimes doctors recommend screening tests (see ), which are tests that are done to look for disorders in people who have no symptoms. Women with gynecologic symptoms sometimes need to have diagnostic procedures done....
Overview of the Pituitary Gland
Feb 1, 2007
The pituitary is a pea-sized gland that is housed within a bony structure (sella turcica) at the base of the brain. The sella turcica protects the pituitary but allows very little room for expansion....
Enlargement of the Pituitary Gland
Feb 1, 2007
Enlargement of the pituitary gland is usually due to a tumor but may be due to bleeding into the gland or involvement by some other disease, such as tuberculosis or sarcoidosis. An enlarged pituitary gland may produce symptoms such as headaches. Beca...
Hypopituitarism
Feb 1, 2007
Hypopituitarism is an underactive pituitary gland that results in deficiency of one or more pituitary hormones.
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Central Diabetes Insipidus
Feb 1, 2007
Central diabetes insipidus is a lack of antidiuretic hormone that causes excessive production of very dilute urine (polyuria).
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Acromegaly and Gigantism
Feb 1, 2007
Overproduction of growth hormone causes excessive growth. In children, the condition is called gigantism. In adults, it is called acromegaly.
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Galactorrhea
Feb 1, 2007
Galactorrhea is the production of breast milk in men or in women who are not breastfeeding.
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Empty Sella Syndrome
Feb 1, 2007
In empty sella syndrome, the sella turcica (the bony structure at the base of the brain that houses the pituitary gland) enlarges, but the pituitary remains normal-sized or shrinks.
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Overview of Prion Diseases
Jan 1, 2007
Prion diseases (transmissible spongiform encephalopathies) are rare degenerative diseases of the brain thought to be caused by a protein that converts to an abnormal form called a prion.
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Creutzfeldt-Jakob Disease (CJD)
Jan 1, 2007
Creutzfeldt-Jakob disease (subacute spongiform encephalopathy) is a prion disease characterized by progressive deterioration of mental function, leading to dementia, muscle twitching (myoclonus), and staggering when walking. A variant form i...
Fatal Familial Insomnia
Jan 1, 2007
Fatal familial insomnia is a rare prion disease that interferes with sleep and leads to deterioration of mental and motor functions. Death occurs within a few months to a few years.
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Gerstmann-Sträussler-Scheinker Disease
Jan 1, 2007
Gerstmann-Sträussler-Scheinker disease is a prion disease that causes muscle incoordination followed by slow deterioration of mental function. The disease is fatal, usually in about 5 years.
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Kuru
Jan 1, 2007
Kuru is a prion disease that causes rapid deterioration of mental function and loss of muscle coordination. This disease used to occur in the Fore natives of the New Guinea highlands and is related to ritual endocannibalism.
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Introduction
Dec 1, 2006
The kidneys filter and cleanse the blood. They also maintain the body's balance of water, dissolved salts (electrolytes, such as sodium, potassium, and calcium), and nutrients in the blood. The kidneys begin these tasks by filtering the blood as it f...
Renal Tubular Acidosis (RTA)
Dec 1, 2006
In renal tubular acidosis, the kidney tubules cannot adequately remove acids from the blood to excrete them in the urine.
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Renal Glucosuria
Dec 1, 2006
In renal glucosuria (glycosuria), glucose (sugar) is excreted in the urine, despite normal or low glucose levels in the blood.
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Nephrogenic Diabetes Insipidus
Dec 1, 2006
In nephrogenic diabetes insipidus, the kidneys produce a large volume of dilute urine because they fail to respond to antidiuretic hormone and are unable to concentrate urine.
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Cystinuria
Dec 1, 2006
Cystinuria is a rare disorder that results in excretion of the amino acid cystine into the urine, often causing cystine stones to form in the urinary tract.
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Fanconi Syndrome
Dec 1, 2006
Fanconi syndrome is a rare disorder of tubule function that results in excess amounts of glucose, bicarbonate, phosphates (phosphorus salts), uric acid, potassium, sodium, and certain amino acids being excreted in the urine.
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Hypophosphatemic Rickets
Dec 1, 2006
Hypophosphatemic rickets (previously called vitamin D–resistant rickets) is a disorder in which the bones become painfully soft and bend easily because the blood contains low levels of phosphate.
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Hartnup Disease
Dec 1, 2006
Hartnup disease is a rare hereditary disorder that results in a skin rash and brain abnormalities because tryptophan and certain other amino acids are not well absorbed from the intestine and not well reabsorbed by the kidneys.
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Bartter Syndrome
Dec 1, 2006
In Bartter syndrome, the kidneys excrete excessive amounts of electrolytes (potassium, sodium, and chloride), resulting in electrolyte abnormalities in the blood.
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Liddle Syndrome
Dec 1, 2006
Liddle syndrome is a rare hereditary disorder in which the kidneys excrete potassium but retain too much sodium and water, leading to high blood pressure.
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Polycystic Kidney Disease (PKD)
Dec 1, 2006
Polycystic kidney disease is a hereditary disorder in which many fluid-filled sacs (cysts) form in both kidneys. The kidneys grow larger but have less functioning tissue.
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Nephronophthisis–Medullary Cystic Disease Complex
Dec 1, 2006
Nephronophthisis–medullary cystic disease complex is a group of disorders in which fluid-filled sacs (cysts) develop deep within the kidneys, leading to kidney failure.
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Medullary Sponge Kidney
Dec 1, 2006
Medullary sponge kidney is an uncommon disorder in which the urine-containing tubules of the kidneys are dilated.
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Introduction
Dec 1, 2006
Itching and rashes may develop as the result of infection or irritation or from a reaction of the immune system. Some rashes occur mostly in children (see ), whereas others almost always occur in adults. Sometimes an immune reaction is triggered by s...
Itching
Dec 1, 2006
Itching (pruritus) is a sensation that instinctively demands scratching.
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Dermatitis
Dec 1, 2006
Dermatitis (eczema) is inflammation of the upper layers of the skin, causing itching, blisters, redness, swelling, and often oozing, scabbing, and scaling.
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Drug Rashes
Dec 1, 2006
Drug rashes are a side effect of a drug that manifests as a skin reaction.
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Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis
Dec 1, 2006
Stevens-Johnson syndrome and toxic epidermal necrolysis are two forms of the same life-threatening skin disease that cause rash, skin peeling, and sores on the mucous membranes.
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Erythema Multiforme
Dec 1, 2006
Erythema multiforme is a recurring disorder characterized by patches of red, raised skin that often look like targets and usually are distributed symmetrically over the body.
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Erythema Nodosum
Dec 1, 2006
Erythema nodosum is an inflammatory disorder that produces tender red bumps (nodules) under the skin, most often over the shins but occasionally on the arms and other areas.
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Granuloma Annulare
Dec 1, 2006
Granuloma annulare is a chronic, harmless skin disorder of unknown cause in which small, firm, raised bumps form a ring with normal or slightly sunken skin in the center.
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Psoriasis
Dec 1, 2006
Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin.
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Pityriasis Rosea
Dec 1, 2006
Pityriasis rosea is a mild disease that causes the formation of many small patches of scaly, rose-colored, inflamed skin.
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Rosacea
Dec 1, 2006
Rosacea (acne rosacea) is a persistent skin disorder that produces redness, tiny pimples, and noticeable blood vessels, usually on the central area of the face.
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Lichen Planus
Dec 1, 2006
Lichen planus, a recurring itchy disease, starts as a rash of small, discrete red or purple bumps that then combine and become rough, scaly patches.
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Keratosis Pilaris
Dec 1, 2006
Keratosis pilaris is a common disorder in which dead cells shed from the upper layer of skin plug the openings of hair follicles.
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Abnormal Eye Sensation
Dec 1, 2006
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Changes in the Appearance of the Eyes
Dec 1, 2006
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Changes in Vision
Dec 1, 2006
Changes in vision may involve loss of vision or distortion of vision. People often describe either type of change as blurring of vision....
Introduction
Dec 1, 2006
A person who experiences eye symptoms should be checked by a doctor. However, some eye diseases cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2 years or more frequently if there is an eye conditio...
The Eye Examination
Dec 1, 2006
A person with eye or vision problems describes the location and duration of the symptoms, and then the doctor examines the eye, the area around it, and possibly other parts of the body, depending on the suspected cause. An eye examination usually inc...
Tests for Eye Disorders
Dec 1, 2006
A variety of tests can be carried out to confirm a problem or to determine the extent or severity of the disorder. Each eye is tested separately....
Cerebral Palsy (CP)
Dec 1, 2006
Cerebral palsy refers to a group of symptoms including poor muscle control, spasticity, paralysis, and other neurologic problems resulting from brain injury before, during, or shortly after birth.
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Introduction
Dec 1, 2006
People expect doctors to use treatments that work well and to stop using those that do not. However, it is often difficult for doctors and other scientists to tell which treatments work. Making this distinction is part of the science of medicine and ...
The Science of Medicine
Dec 1, 2006
Doctors have been treating people for many thousands of years. The earliest written description of medical treatment is from ancient Egypt and is over 3,500 years old. Even before that, healers and shamans were likely providing herbal and other remed...
What Participants Need to Know About Clinical Trials
Dec 1, 2006
Clinical trials are experiments designed to find out whether an intervention is safe and effective. The intervention is most often a drug but can also be a device, such as a pacemaker or stent, or a diagnostic tool, such as a blood test. Participatio...
Cough
Nov 1, 2006
A cough is a sudden, explosive exhalation of air; the function of a cough is to clear material from the airways.
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Dyspnea
Nov 1, 2006
Dyspnea (shortness of breath) is the unpleasant sensation of difficulty in breathing.
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Chest Pain
Nov 1, 2006
Chest pain may be described as sharp (possibly knifelike), dull, burning, or squeezing; it may be located in a specific spot on the chest (such as the chest wall) or may be difficult to locate, often feeling like a deep ache. The pain may be constant...
Wheezing
Nov 1, 2006
Wheezing is a whistling, musical sound during breathing resulting from partially obstructed airways.
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Stridor
Nov 1, 2006
Stridor is a gasping sound during inhalation resulting from a partial blockage of the throat (pharynx), voice box (larynx), or windpipe (trachea).
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Hemoptysis
Nov 1, 2006
Hemoptysis is the coughing up of blood from the respiratory system.
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Cyanosis
Nov 1, 2006
Cyanosis is a bluish discoloration of the skin resulting from an inadequate amount of oxygen in the blood.
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Clubbing
Nov 1, 2006
Clubbing is an enlargement of the tips of the fingers or toes and a change in the angle where the nails emerge.
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Medical History and Physical Examination
Nov 1, 2006
A doctor first asks the person about symptoms. Chest pain, shortness of breath (dyspnea) either at rest or during exertion, cough, coughing up of sputum or blood (hemoptysis), and wheezing may indicate a lung or airway disorder. Other, more general s...
Tests for Lung Disorders
Nov 1, 2006
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Overview of the Autonomic Nervous System
Nov 1, 2006
The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person's conscious effort....
Autonomic Neuropathies
Nov 1, 2006
Autonomic neuropathies are disorders affecting the peripheral nerves that particularly damage the nerves that automatically (without conscious effort) regulate body processes (autonomic nerves).
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Horner's Syndrome
Nov 1, 2006
In Horner's syndrome, on one side of the face, the eyelid droops, the pupil is small (constricted), and sweating is decreased. The cause is disruption of the nerve fibers that connect the eye and the brain.
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Pure Autonomic Failure
Nov 1, 2006
Pure autonomic failure is dysfunction of many of the processes controlled by the autonomic nervous system, such as blood pressure. It is not fatal.
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Overview of Mouth Growths
Nov 1, 2006
Noncancerous (benign) growths, precancerous (dysplastic) changes, and cancerous (malignant) growths can originate in any type of tissue in and around the mouth, including bone, muscle, and nerve. Most commonly, growths form on the lips, the sides of ...
Noncancerous Mouth Growths
Nov 1, 2006
A variety of growths that are noncancerous may occur in and around the mouth. A lump or raised area on the gums (gingiva) is not a cause for alarm. Such a lump may be caused by a gum or tooth abscess or by irritation. Noncancerous growths due to irri...
Precancerous Changes in the Mouth
Nov 1, 2006
White, red, or mixed white-red areas that are not easily wiped away, persist for more than 2 weeks, and are not definable as some other condition may be precancerous. The same risk factors are involved in precancerous chang...
Cancerous Mouth Growths
Nov 1, 2006
Each year, cancer of the mouth (oral cancer) develops in 30,000 people in the United States and causes 8,000 deaths, mostly in people older than 50. Oral cancer represents more than 2% of all cancers and 1.5% of all cancer-related deaths—a high rate ...
Hypoglycemia
Nov 1, 2006
Hypoglycemia is abnormally low levels of sugar (glucose) in the blood.
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Initial Care of the Newborn
Nov 1, 2006
Immediately after a baby is born, the doctor or nurse gently clears mucus and other material from the mouth, nose, and throat with a suction bulb. The newborn is then able to take a breath. Two clamps are placed on the newborn's umbilical cord, side ...
Physical Examination of the Newborn
Nov 1, 2006
The doctor usually gives the newborn a thorough physical examination within the first 12 hours of life. The examination begins with a series of measurements, including weight, length, and head circumference. The average weight at birth is 7 pounds, a...
First Few Days After Birth
Nov 1, 2006
Immediately after a normal birth, the mother and father are encouraged to hold their newborn. Breastfeeding should be initiated as soon after birth as possible if the mother plans to breastfeed. Breastfeeding stimulates oxytocin, a hormone that helps...
Feeding of Newborns and Infants
Nov 1, 2006
A normal newborn has active rooting and sucking reflexes and can start feeding right away, so doctors recommend placing the newborn at the mother's breast immediately after birth. If this is not done, feedings are begun at least within 4 hours after ...
Stools and Urine in Infants
Nov 1, 2006
Infants typically urinate 15 to 20 times per day. The urine varies in color from nearly clear to dark yellow. Stools vary a great deal among infants in frequency, color, and consistency depending on the nature of the individual infants and the conten...
Sleeping in Newborns and Infants
Nov 1, 2006
Because the nervous system of newborns is immature, newborns sleep a great deal, but only for an hour or two at a time, independent of day or night. By 4 to 6 weeks of age, many infants are on a cycle of waking for 4 hours and sleeping for 4 hours. O...
Physical Development of Infants
Nov 1, 2006
An infant's physical development depends on heredity, nutrition, and environment. Physical and psychologic abnormalities can also influence growth. Optimal growth requires optimal nutrition and health....
Behavioral, Social, and Intellectual Development of Infants
Nov 1, 2006
The rate of behavioral, social, and intellectual development varies considerably from infant to infant. Some infants develop faster, although certain patterns may run in families, such as late walking or talking. Environmental factors, such as lack o...
Promoting Optimal Development of Infants
Nov 1, 2006
Babies obviously require appropriate food and shelter for their physical growth. If their physical needs are met regularly and consistently, babies quickly learn that their caretaker is a source of satisfaction, creating a firm bond of trust and atta...
Preventive Health Care Visits for Infants
Nov 1, 2006
Healthy infants should be seen by their doctor often during the first year of life. Visits typically take place by 1 to 2 weeks, and at 2, 4, 6, 9, and 12 months of age. During these visits, the doctor monitors the infant's growth and development by ...
Vaccination of Infants and Children
Nov 1, 2006
Children should be vaccinated to protect them against infectious diseases. Vaccines are preparations that contain either noninfectious fragments of bacteria or viruses or whole forms of these organisms that have been weakened so that they do not caus...
Lip Disorders
Oct 1, 2006
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Tongue Disorders
Oct 1, 2006
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Mouth Sores
Oct 1, 2006
Mouth sores vary in appearance and size and can affect any part of the mouth, inside and outside. Some sores may be raised, usually filled with fluid (in which case they are called vesicles or bullae, depending on size), whereas others may be ulcers....
Recurrent Aphthous Stomatitis
Oct 1, 2006
Recurrent aphthous stomatitis (canker sores, aphthous ulcers) is small, painful sores inside the mouth that typically begin in childhood and recur frequently.
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Definition of Peptic Disorders
Oct 1, 2006
Peptic disorders include gastritis, peptic ulcer, and gastroesophageal reflux. They involve damage to the lining of the esophagus, stomach, or duodenum (the first segment of the small intestine). These disorders are usually caused by stomach acids (e...
Gastritis
Oct 1, 2006
Gastritis is inflammation of the stomach lining.
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Peptic Ulcer
Oct 1, 2006
A peptic ulcer is a round or oval sore where the lining of the stomach or duodenum has been eaten away by stomach acid and digestive juices.
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Gastroesophageal Reflux (GERD)
Oct 1, 2006
In gastroesophageal reflux (gastroesophageal reflux disease [GERD]), stomach acid and enzymes flow backward from the stomach into the esophagus, causing inflammation and pain in the esophagus.
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Tests for Liver, Gallbladder, and Biliary Disorders
Oct 1, 2006
A variety of diagnostic tests help doctors assess disorders of the liver, gallbladder, and biliary tract (the ducts that connect the liver and gallbladder and that transport bile). Among the most important are a group of blood tests known as liver fu...
Warning Signs of Cancer
Oct 1, 2006
Cancer can cause many different symptoms, some subtle and some not at all subtle. Some symptoms develop early in the course of cancer and are therefore important warning signs that should be evaluated by a doctor. Other symptoms develop only...
Symptoms of Cancer
Oct 1, 2006
At first, cancer, as a tiny mass of cells, causes no symptoms whatsoever. As a cancer grows, its physical presence can affect nearby tissues. Also, some cancers secrete certain substances or trigger immune reactions that cause symptoms in other parts...
Diagnosis of Cancer
Oct 1, 2006
Cancer is suspected based on a person's symptoms, the results of a physical examination, and sometimes the results of screening tests. Occasionally, x-rays obtained for other reasons, such as an injury, show abnormalities that might be cancer. Confir...
Overview of the Skin
Oct 1, 2006
The skin is the body's largest organ. It serves many important functions, including regulating body temperature, maintaining water and electrolyte balance, and sensing painful and pleasant stimuli. The skin keeps vital chemicals and nutrients in the ...
Structure and Function of the Skin
Oct 1, 2006
The skin has three layers—the epidermis, dermis, and fat layer (also called the subcutaneous layer). Each layer performs specific tasks....
Effects of Aging on the Skin
Oct 1, 2006
Aging results in thinning of the dermis and epidermis. The underlying fat can be lost as well. The decrease in volume and overall effectiveness of all three skin layers results in a number of important medical and cosmetic effects. The skin loses som...
Description of Skin Marks and Growths
Oct 1, 2006
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Diagnosis of Skin Disorders
Oct 1, 2006
Doctors can identify many skin disorders simply by looking at the skin. Revealing characteristics include size, shape, color, and location of the abnormality as well as the presence or absence of other symptoms or signs. To check the distribution of ...
Treatment of Skin Disorders
Oct 1, 2006
Topical drugs (drugs applied directly to the skin) are a mainstay of treating skin disorders. Systemic drugs are taken by mouth or given by injection and are distributed throughout the body. Rarely, when a high concentration of a drug is needed at th...
Introduction
Sep 1, 2006
The lungs are particularly prone to allergic reactions because they are exposed to large quantities of airborne substances that commonly cause allergic reactions (called antigens), including dusts, pollens, fungi, and chemicals. Exposure to irritatin...
Hypersensitivity Pneumonitis
Sep 1, 2006
Hypersensitivity pneumonitis (extrinsic allergic alveolitis) is a type of inflammation in and around the tiny air sacs (alveoli) and smallest airways (bronchioles) of the lung caused by an allergic reaction to inhaled organic dusts or, less ...
Eosinophilic Pneumonia
Sep 1, 2006
Eosinophilic pneumonia (also called pulmonary infiltrates with eosinophilia syndrome) comprises a group of lung diseases in which eosinophils (a type of white blood cell) appear in increased numbers in the lungs and usually in the bloodstrea...
Allergic Bronchopulmonary Aspergillosis
Sep 1, 2006
Allergic bronchopulmonary aspergillosis is an allergic lung reaction to a type of fungus (most commonly Aspergillus fumigatus) that occurs in some people with asthma or cystic fibrosis.
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Goodpasture's Syndrome
Sep 1, 2006
Goodpasture's syndrome is an uncommon autoimmune disorder in which bleeding into the lungs and progressive kidney failure occur.
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Physical Examination
Sep 1, 2006
A doctor looks for certain things during a physical examination depending on what disorder is suspected. When evaluating bones, if a fracture is suspected (see ), the doctor may notice that the affected part (such as an arm or a leg) is abnormally sh...
Tests for Musculoskeletal Disorders
Sep 1, 2006
A doctor can often diagnose a musculoskeletal disorder based on the symptoms and on the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes necessary to help the doctor make or confirm a di...
Joint Noises
Sep 1, 2006
Joint noises, such as creaks and clicks, are common in many people, but they can also occur with specific problems of the joints. For example, the base of the knee cap may creak when it is damaged by osteoarthritis, and the jaw may click in a person ...
Joint Stiffness
Sep 1, 2006
Stiffness is the feeling that motion of a joint is limited or difficult. The feeling is not caused by weakness or reluctance to move the joint due to pain. Some people with stiffness are capable of moving the joint through its full range of motion. J...
Difficulty Moving
Sep 1, 2006
A person may have difficulty moving all or part of the body....
Musculoskeletal Pain
Sep 1, 2006
Pain is the chief symptom of most musculoskeletal disorders. The pain may be mild or severe, local or widespread (diffuse). Although pain may be acute and short-lived, as is the case with most injuries, pain may be ongoing with chronic illnesses, suc...
Clostridium difficile-Induced Colitis
Sep 1, 2006
Clostridium difficile-induced colitis (also called antibiotic-associated colitis and pseudomembranous colitis) is inflammation of the large intestine that results in diarrhea. The inflammation is caused by the growth of unusual ba...
Overview of the Urinary Tract
Sep 1, 2006
Normally, a person has two kidneys. The rest of the urinary tract consists of two ureters (the tubes connecting each kidney to the bladder), the bladder, and the urethra (a tube attached to the bladder that leads to the outside of the body). Each kid...
Kidneys
Sep 1, 2006
The kidneys are bean-shaped organs, each about 4 to 5 inches (12 centimeters) long. One lies on each side of the spinal column, just behind the abdominal cavity, which contains the digestive organs. Each kidney receives blood through a branch of the ...
Ureters
Sep 1, 2006
The ureters are muscular tubes—about 16 inches (40 centimeters) long—that attach at their upper end to the kidneys and at their lower end to the bladder....
Bladder
Sep 1, 2006
The bladder is an expandable, muscular sac. Urine accumulates in the bladder as it arrives from the ureters....
Urethra
Sep 1, 2006
The urethra is a tube that drains urine from the bladder out of the body. In men, the urethra is about 8 inches (20 centimeters) long, ending at the tip of the penis. In women, the urethra is about 1½ inches (4 centimeters) long, ending at the vulva....
Effects of Aging on the Urinary Tract
Sep 1, 2006
As people age, there is a slow, steady decline in the weight of the kidneys. After about age 30 to 40, about two thirds of people (even those who do not have kidney disease) undergo a gradual decline in the rate at which their kidneys filter blood. H...
Overview of Liver Disease
Aug 31, 2006
Liver disease can manifest in many different ways. Characteristic manifestations include jaundice (a yellowish discoloration of the skin and whites of the eyes), cholestasis (reduction or stoppage of bile flow), liver enlargement, portal hypertension...
Jaundice
Aug 31, 2006
Jaundice is a yellowish discoloration of the skin and of the whites of the eyes caused by abnormally high levels of the pigment bilirubin in the bloodstream.
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Cholestasis
Aug 31, 2006
Cholestasis is reduction or stoppage of bile flow.
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Portal Hypertension
Aug 31, 2006
Portal hypertension is abnormally high blood pressure in branches of the portal vein, the large vein that brings blood from the intestine to the liver.
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Ascites
Aug 31, 2006
Ascites is the accumulation of protein-containing (ascitic) fluid in the abdominal cavity.
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Hepatic Encephalopathy
Aug 31, 2006
Hepatic encephalopathy (portal-systemic encephalopathy, liver encephalopathy, hepatic coma) is deterioration of brain function that occurs because toxic substances normally removed by the liver build up in the blood and reach the brain.
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Liver Failure
Aug 31, 2006
Liver failure is severe deterioration in liver function.
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Overview of Blood
Aug 31, 2006
Blood is a complex mixture of plasma (the liquid component), white blood cells, red blood cells, and platelets. The body contains about 5 to 6 quarts (about 5 liters) of blood. Once blood is pumped out of the heart, it takes 20 to 30 seconds to make ...
Components of Blood
Aug 31, 2006
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Formation of Blood Cells
Aug 31, 2006
Red blood cells, most white blood cells, and platelets are produced in the bone marrow, the soft fatty tissue inside bone cavities. Two types of white blood cells, T and B lymphocytes, are also produced in the lymph nodes and spleen, and T lymphocyte...
Effects of Aging on the Blood
Aug 31, 2006
Aging has some effect on bone marrow and blood cells. The amount of fat in the marrow increases with age, which means there is less cell-producing marrow. While this decrease generally does not cause problems, it may when the body experiences an incr...
Overview of Pericardial Disease
Aug 25, 2006
Pericardial disease affects the pericardium, which is the flexible two-layered sac that envelops the heart.
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Acute Pericarditis
Aug 25, 2006
Acute pericarditis is inflammation of the pericardium that begins suddenly, is often painful, and causes fluid and blood components such as fibrin, red blood cells, and white blood cells to pour into the pericardial space.
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Chronic Pericarditis
Aug 25, 2006
Chronic pericarditis is inflammation that begins gradually, is long-lasting, and results in fluid accumulation in the pericardial space or thickening of the pericardium.
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Overview of the Digestive System
Aug 21, 2006
The digestive system, which extends from the mouth to the anus, is responsible for receiving food, breaking it down into nutrients (a process called digestion), absorbing the nutrients into the bloodstream, and eliminating the indigestible parts of f...
Throat and Esophagus
Aug 21, 2006
The throat (pharynx) lies behind and below the mouth. When food and fluids leave the mouth, they pass through the throat. Swallowing of food and fluids begins voluntarily and continues automatically. A small muscular flap (epiglottis) closes to preve...
Stomach
Aug 21, 2006
The stomach is a large, bean-shaped, hollow muscular organ consisting of three regions: the cardia, the body (fundus), and the antrum. Food and fluids enter the stomach from the esophagus by passing through the lower esophageal sphincter....
Small Intestine
Aug 21, 2006
The stomach releases food into the duodenum, which is the first segment of the small intestine. Food enters the duodenum through the pyloric sphincter in amounts that the small intestine can digest. When full, the duodenum signals the stomach to stop...
Pancreas
Aug 21, 2006
The pancreas is an organ that contains two basic types of tissue: the acini, which produce digestive enzymes, and the islets, which produce hormones. The pancreas secretes digestive enzymes into the duodenum and hormones into the bloodstream....
Liver
Aug 21, 2006
The liver is a large organ with several functions (see ), only some of which are related to digestion....
Gallbladder and Biliary Tract
Aug 21, 2006
Bile flows out of the liver through the right and left hepatic ducts (see ), which come together to form the common hepatic duct. This duct then joins with a duct coming from the gallbladder, called the cystic duct, to form the common bile duct. The ...
Large Intestine
Aug 21, 2006
The large intestine consists of the cecum and ascending (right) colon, the transverse colon, the descending (left) colon, and the sigmoid colon, which is connected to the rectum. The cecum, which is at the beginning of the ascending colon, is the poi...
Rectum and Anus
Aug 21, 2006
The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus. Ordinarily, the rectum is empty because stool is stored higher in the descending colon. Eventually, the descending c...
Effects of Aging on the Digestive System
Aug 21, 2006
Because the digestive system has a lot of reserve built into it, aging has relatively little effect on its function compared to its effects on other organ systems. Nonetheless, aging is a factor in several digestive system disorders. In particular, o...
Overview of Inflammatory Bowel Disease
Aug 21, 2006
In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal cramps and diarrhea.
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Crohn's Disease
Aug 21, 2006
Crohn's disease (regional enteritis, granulomatous ileitis, ileocolitis) is a chronic inflammation of the intestinal wall that may affect any part of the digestive tract.
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Ulcerative Colitis
Aug 21, 2006
Ulcerative colitis is a chronic disease in which the large intestine becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of bloody diarrhea, abdominal cramps, and fever. The long-term risk of colon canc...
Collagenous Colitis and Lymphocytic Colitis
Aug 21, 2006
Collagenous colitis and lymphocytic colitis are chronic diseases, characterized by watery diarrhea, in which certain kinds of white blood cells infiltrate the lining of the large intestine.
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Diversion Colitis
Aug 21, 2006
Diversion colitis is inflammation that develops in a lower part of the large intestine after the passage of stool above this part has been surgically diverted.
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Introduction
Aug 1, 2006
To sustain life, the body must produce sufficient energy. Energy is produced by burning molecules in food, which is done by the process of oxidation (whereby food molecules are combined with oxygen). Oxidation involves carbon and hydrogen being combi...
Respiratory System
Aug 1, 2006
The respiratory system starts at the nose and mouth and continues through the airways and the lungs. Air enters the respiratory system through the nose and mouth and passes down the throat (pharynx) and through the voice box, or larynx. The entrance ...
Chest Cavity
Aug 1, 2006
The lungs are housed in the chest cavity, a space that also includes the mediastinum. The mediastinum is in the center of the chest and contains the heart, thymus, and lymph nodes, along with portions of the aorta, vena cava, trachea, esophagus, and ...
Exchanging Oxygen and Carbon Dioxide
Aug 1, 2006
The primary function of the respiratory system is to exchange oxygen and carbon dioxide. Inhaled oxygen enters the lungs and reaches the alveoli. The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and ...
Control of Breathing
Aug 1, 2006
Breathing is usually automatic, controlled subconsciously by the respiratory center at the base of the brain. Breathing continues during sleep and usually even when a person is unconscious. People can also control their breathing when they wish, for ...
Defense Mechanisms
Aug 1, 2006
The average person who is moderately active during the daytime breathes about 20,000 liters of air every 24 hours. Inevitably, this air (which would weigh more than 20 kilograms) contains potentially harmful particles and gases. Particles, such as du...
Effects of Aging
Aug 1, 2006
The effects of aging on the respiratory system are similar to those that occur in other organs: maximum function gradually declines. Age-related changes in the lungs include decreases in the peak airflow, gas exchange, and vital capacity (the maximum...
Structure and Function of the Eyes
Aug 1, 2006
The orbit is the bony cavity that contains the eyeball, muscles, nerves, and blood vessels, as well as the structures that produce and drain tears. Each orbit is a pear-shaped structure that is formed by several bones....
Muscles, Nerves, and Blood Vessels of the Eyes
Aug 1, 2006
Several muscles working together move the eye, allowing people to look in different directions without moving their head. Each eye muscle is stimulated by a specific cranial nerve (see ). The optic nerve (a cranial nerve), which carries impulses from...
Protective Features of the Eyes
Aug 1, 2006
The bony structures of the orbit protrude beyond the surface of the eye. They protect the eye while allowing it to move freely in a wide arc....
Effects of Aging on the Eyes
Aug 1, 2006
In middle age, the lens of the eye becomes less flexible and less able to thicken, and thus less able to focus on nearby objects, a condition called presbyopia. Reading glasses, or bifocal lenses, can help compensate for this problem....
Overview of the Liver and Gallbladder
Jul 21, 2006
Located in the upper right portion of the abdomen, the liver and gallbladder are interconnected by ducts known as the biliary tract, which drains into the first segment of the small intestine (the duodenum). Although the liver and gallbladder partici...
Liver
Jul 21, 2006
The wedge-shaped liver is the largest—and, in some ways, the most complex—organ in the body. It serves as the body's chemical factory, performing many vital functions, from regulating the levels of chemicals in the body to producing substances that m...
Gallbladder and Biliary Tract
Jul 21, 2006
The gallbladder is a small, pear-shaped, muscular storage sac that holds bile. Bile is a greenish yellow, thick, sticky fluid. It consists of bile salts, electrolytes (dissolved charged particles, such as sodium and bicarbonate), bile pigments, chole...
Effects of Aging on the Liver
Jul 21, 2006
A number of structural and microscopic changes occur as the liver ages. For example, the color of the liver changes from lighter to darker brown. Its size and blood flow decrease. However, liver function test results generally remain normal....
Hiatus Hernia
Jun 26, 2006
Hiatus hernia is a protrusion of a portion of the stomach across the opening in the diaphragm that the esophagus normally passes through.
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Bezoars and Foreign Bodies of the Digestive Tract
Jun 26, 2006
Bezoars are tightly packed collections of partially digested or undigested material stuck in the stomach or other parts of the digestive tract. Foreign bodies are small ingested objects that can also get stuck in the digestive tra...
Overview of Bacterial Infections in Childhood
Jun 1, 2006
Bacteria are microscopic, single-celled organisms (see ). Only some bacteria cause disease in people. The most common bacterial infections among children are skin infections (including impetigo), ear infections, and throat infections (strep throat). ...
Occult Bacteremia
Jun 1, 2006
Occult (hidden) bacteremia is the presence of bacteria in the bloodstream of a child who has a fever but who may not appear particularly sick and who has no apparent other source of infection.
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Meningitis in Children
Jun 1, 2006
Bacterial meningitis is infection of the layers of tissue covering the brain and spinal cord (meninges).
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Diphtheria
Jun 1, 2006
Diphtheria is a contagious, sometimes fatal infection of the upper respiratory tract caused by the bacterium Corynebacterium diphtheriae.
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Retropharyngeal Abscess
Jun 1, 2006
A retropharyngeal abscess is a collection of pus in the lymph nodes at the back of the throat.
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Epiglottitis
Jun 1, 2006
Epiglottitis is a severe bacterial infection of the epiglottis, which can block the windpipe, obstructing air flow.
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Pertussis
Jun 1, 2006
Pertussis (whooping cough) is a highly contagious infection caused by the bacterium Bordetella pertussis, which results in fits of coughing that usually end in a prolonged, high-pitched, deeply indrawn breath (the whoop).
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Rheumatic Fever
Jun 1, 2006
Rheumatic fever is inflammation of the body's organ systems, especially the joints and the heart, resulting from a complication of streptococcal infection of the throat.
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Urinary Tract Infection in Children(UTI)
Jun 1, 2006
A urinary tract infection is a bacterial infection of the urinary bladder (cystitis) or the kidneys (pyelonephritis).
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Overview of Child Neglect and Abuse
May 31, 2006
Children can be mistreated by having essential things withheld from them (neglect) or by having harmful things done to them (abuse). Neglect involves not meeting children's basic needs: physical, medical, educational, and emotional. Emotional neglect...
Female Genital Mutilation
May 31, 2006
Female genital mutilation is ritual removal of part or all of the clitoris and labia.
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Personality Disorders
May 30, 2006
Personality disorders are patterns of perceiving, reacting, and relating to other people and events that are relatively inflexible and that impair a person's ability to function socially.
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How Blood Clots
May 18, 2006
Hemostasis is the body's way of stopping injured blood vessels from bleeding. Hemostasis includes clotting of the blood. Too much clotting can block blood vessels that are not bleeding; consequently, the body has control mechanisms ...
Hereditary Hemorrhagic Telangiectasia
May 18, 2006
Hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease) is a hereditary disorder in which blood vessels are malformed, making them fragile and prone to bleeding.
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Thrombocytopenia (ITP, TTP)
May 18, 2006
Thrombocytopenia is a deficiency of platelets (thrombocytes).
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Von Willebrand's Disease
May 18, 2006
Von Willebrand's disease is a hereditary deficiency or abnormality of the blood protein von Willebrand factor, which affects platelet function.
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Hemophilia
May 18, 2006
Hemophilia is a bleeding disorder caused by a deficiency in one of two blood clotting factors: factor VIII or factor IX.
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Thrombophilia
May 18, 2006
Thrombophilia is a disorder in which the blood clots easily or excessively.
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Disseminated Intravascular Coagulation (DIC)
May 18, 2006
Disseminated intravascular coagulation is a condition in which small blood clots develop throughout the bloodstream, blocking small blood vessels. The increased clotting depletes the platelets and clotting factors needed to control bleeding,...
Introduction
May 16, 2006
Between the ages of 1 and 13, children's physical, intellectual, and emotional capabilities expand tremendously. Children progress from barely tottering to running, jumping, and playing organized sports. At age 1, most children can utter only a few r...
Physical Development
May 16, 2006
Physical growth begins to slow at around age 1. As growth slows, children need fewer calories and parents may notice a decrease in appetite. Two-year-old children can have very erratic eating habits that sometimes make parents anxious. It seems as th...
Intellectual Development
May 16, 2006
At the age of 2, most children understand the concept of time in broad terms. Many 2- and 3-year-old children believe that anything that happened in the past happened "yesterday," and anything that will happen in the future will happen "tomorrow." A ...
Social and Emotional Development
May 16, 2006
Emotion and behavior are based on the child's developmental stage and temperament. Every child has an individual temperament, or mood. Some children may be cheerful and adaptable and easily develop regular routines of sleeping, waking, eating, and ot...
Promoting Optimal Health and Development
May 16, 2006
Parents can help their children achieve the best possible health. For example, they can help prevent obesity by establishing healthy eating patterns and promoting regular exercise. Children should consume a variety of healthy foods, including fruits ...
Preventive Health Care Visits
May 16, 2006
Scheduled visits to the doctor provide parents with information about their child's growth and development. Such visits also give parents an opportunity to ask questions and seek advice. The American Academy of Pediatrics recommends that after the fi...
Overview of Heart Valve Disorders
May 15, 2006
Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles—see ). Each ventricle has a one-way "in" (inlet) valve and a one-way "out" (outle...
Mitral Regurgitation
May 15, 2006
Mitral regurgitation (mitral valve regurgitation, mitral incompetence, mitral insufficiency) is leakage of blood backward through the mitral valve each time the left ventricle contracts.
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Mitral Valve Prolapse (MVP)
May 15, 2006
Mitral valve prolapse (MVP) is a disorder in which the valve cusps bulge into the left atrium when the left ventricle contracts, sometimes allowing leakage (regurgitation) of small amounts of blood into the atrium.
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Mitral Stenosis
May 15, 2006
Mitral stenosis (mitral valve stenosis) is a narrowing of the mitral valve opening that increases resistance to blood flow from the left atrium to the left ventricle.
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Aortic Regurgitation
May 15, 2006
Aortic regurgitation (aortic incompetence, aortic insufficiency) is leakage of blood back through the aortic valve each time the left ventricle relaxes.
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Aortic Stenosis
May 15, 2006
Aortic stenosis is a narrowing of the aortic valve opening that increases resistance to blood flow from the left ventricle to the aorta.
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Tricuspid Regurgitation
May 15, 2006
Tricuspid regurgitation (tricuspid incompetence, tricuspid insufficiency) is leakage of blood backward through the tricuspid valve each time the right ventricle contracts.
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Tricuspid Stenosis
May 15, 2006
Tricuspid stenosis is a narrowing of the tricuspid valve opening that increases resistance to blood flow from the right atrium to the right ventricle.
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Pulmonic Stenosis
May 15, 2006
Pulmonic (pulmonary) stenosis is a narrowing of the pulmonary valve opening that increases resistance to blood flow from the right ventricle to the pulmonary artery. It is often present at birth (congenital) and thus affects children.
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Endocrine Glands
May 15, 2006
The major glands of the endocrine system, each of which produces one or more specific hormones, are the hypothalamus, the pituitary gland, the thyroid gland, the parathyroid glands, the islets of the pancreas, the adrenal glands, the testes in men, a...
Endocrine Function
May 15, 2006
The main function of endocrine glands is to secrete hormones directly into the bloodstream. Hormones are chemical substances that affect the activity of another part of the body (target site). In essence, hormones serve as messengers, controlling and...
Endocrine Controls
May 15, 2006
To control endocrine functions, the secretion of each hormone must be regulated within precise limits. The body is normally able to sense whether more or less of a given hormone is needed....
Endocrine Disorders
May 15, 2006
Endocrine disorders involve either too much or too little hormone secretion. Disorders may result from a problem in the gland itself, or because the hypothalamic-pituitary axis provides too much or too little stimulation. Depending on the type of cel...
Effects of Aging on the Endocrine System
May 15, 2006
Levels of most hormones decrease with aging, but some hormones remain at levels typical of those in younger adults, and some even increase. Even when hormone levels do not decline, endocrine function generally declines with age because hormone recept...
Salivary Gland Disorders
May 11, 2006
There are three major pairs of salivary glands in the mouth. The largest pair of salivary glands, called the parotid glands, lies just behind the angle of the jaw, below and in front of the ears. Two smaller pairs, the sublingual glands and the subma...
Introduction
May 1, 2006
The human body is a complex, highly organized structure made up of unique cells that work together to accomplish the specific functions necessary for sustaining life. The biology of the human body includes structure (anatomy) and function (physiology...
Cells
May 1, 2006
Often thought of as the smallest unit of a living organism, a cell is made up of many even smaller parts, each with its own function. Human cells vary in size, but all are quite small. Even the largest, a fertilized egg, is too small to be seen with ...
Tissues and Organs
May 1, 2006
Related cells joined together are collectively referred to as a tissue. The cells in a tissue are not identical, but they work together to accomplish specific functions. A sample of tissue removed for examination under a microscope (biopsy) contains ...
Organ Systems
May 1, 2006
Although an organ has a specific function, organs also function as part of a group, called an organ system. The organ system is the organizational unit by which medicine is studied, diseases are generally categorized, and treatments are planned. This...
Barriers on the Outside and the Inside
May 1, 2006
As strange as it may seem, defining what is outside and what is inside the body is not always easy, because the body has many surfaces. The skin, which is actually an organ system, is obviously outside the body. It forms a barrier that prevents many ...
Mind-Body Interactions
May 1, 2006
The mind and body interact in powerful ways that affect a person's health. The digestive system is profoundly controlled by the mind (brain); anxiety, depression, and fear dramatically affect the function of this system (see ). Social and psychologic...
Anatomy and Disease
May 1, 2006
The human body is remarkably well designed. Most of its organs have a great deal of extra capacity or reserve: They can still function adequately even when damaged. For example, more than two thirds of the liver must be destroyed before serious conse...
Symptoms of Blood Disorders
May 1, 2006
Symptoms of blood disorders are often vague and nonspecific, that is, they could indicate a disorder of almost any part of the body. However, although no single symptom unmistakably indicates a blood disorder, certain groups of symptoms suggest the p...
Diagnosis of Blood Disorders
May 1, 2006
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Infective Endocarditis
Apr 24, 2006
Infective endocarditis is an infection of the lining of the heart (endocardium) and usually also of the heart valves.
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Overview of Birth Defects
Apr 19, 2006
Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious at birth or by 1 year of age.
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Heart Defects
Apr 19, 2006
One of 120 babies is born with a heart defect. Some are severe, but many are not. Defects may involve abnormal formation of the heart's walls or valves or of the blood vessels that enter or leave the heart....
Urinary Tract Defects
Apr 19, 2006
Birth defects are more common in the kidney and urinary system than in any other system of the body. Defects can develop in the kidneys, the tubes that transport urine from the kidneys to the bladder (ureters), the bladder, or the tube that expels ur...
Genital Defects
Apr 19, 2006
Defects of the external genital organs (penis, testes, or clitoris) usually result from abnormal levels of sex hormones in the fetus before birth. Congenital adrenal hyperplasia (a metabolic disorder) and chromosomal abnormalities commonly cause geni...
Digestive Tract Defects
Apr 19, 2006
A birth defect can occur anywhere along the length of the digestive tract—in the esophagus, stomach, small intestine, large intestine, rectum, or anus. In many cases, an organ is not fully developed or is abnormally positioned, which often causes nar...
Abdominal Wall Defects (Omphalocele and Gastroschisis)
Apr 19, 2006
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Bone and Muscle Defects
Apr 19, 2006
Birth defects can occur in any bone or muscle, although the bones and muscles of the skull, face, spine, hips, legs, and feet are affected most often. Bones and muscles may develop incompletely. Also, structures that normally align together may be se...
Brain and Spinal Cord Defects
Apr 19, 2006
Of the many possible defects in the brain and spinal cord, those known as neural tube defects develop within the first weeks of pregnancy. Others, such as porencephaly and hydranencephaly, develop later in pregnancy. Many brain and spinal cord defect...
Overview of Heart and Blood Vessel Symptoms
Apr 18, 2006
Disorders that affect the heart or blood vessels are called cardiovascular disorders. These disorders are usually divided into heart (cardiac) disorders and peripheral blood vessel disorders. Heart disorders affect the heart and the blood ve...
Chest Pain
Apr 18, 2006
Pain due to a disorder of the heart, lungs, esophagus, or large blood vessels of the trunk is usually felt in the chest, although it can seem to be located anywhere between the upper abdomen and the jaw, including the arms or shoulders. The discomfor...
Palpitations
Apr 18, 2006
Palpitations are the awareness of heart activity. The sensation may feel like pounding, fluttering, racing, or skipping beats....
Shortness of Breath
Apr 18, 2006
Shortness of breath (dyspnea) is the sensation of difficult or labored breathing (see )....
Limitation of Physical Activity
Apr 18, 2006
Heart disorders can limit a person's ability to perform physical activities. One way to evaluate the severity of a heart disorder is to determine how limited this ability is. Doctors may use the New York Heart Association (NYHA) functional class syst...
Fatigue
Apr 18, 2006
When the heart pumps inefficiently as it does in heart failure, blood flow to the muscles may be inadequate during physical activity, causing feelings of weakness and fatigue. Symptoms are often subtle. People usually compensate by gradually reducing...
Light-Headedness and Fainting
Apr 18, 2006
Light-headedness (near-syncope) is the feeling that one is about to faint. Fainting (syncope) is a sudden, brief loss of consciousness followed by spontaneous return of consciousness....
Swelling, Numbness, and Changes in Skin Color
Apr 18, 2006
Swelling is due to the accumulation of fluid (edema) in tissues. It occurs when blood pools in the leg veins, increasing pressure in the leg veins and forcing fluids out of the veins into tissues. Blood may pool because the heart cannot pump...
Pain in the Limbs
Apr 18, 2006
Pain may occur when tissues do not get enough blood (a condition called ischemia). Pain occurs because the tissues do not get enough oxygen, which is carried to tissues by the blood, and because waste products, which are carried away from tissues by ...
Medical History and Physical Examination
Apr 18, 2006
A doctor first asks about symptoms. Chest pain, shortness of breath, palpitations, and swelling in the legs, ankles, and feet or abdomen suggest a heart disorder. Other, more general symptoms, such as fever, weakness, fatigue, lack of appetite, and a...
Tests for Heart and Blood Vessel Disorders
Apr 18, 2006
There are many diagnostic procedures that can help doctors make a rapid, precise diagnosis. They include electrocardiography (ECG), stress testing, electrophysiologic testing, tilt table testing, radiologic procedures (x-rays), ultrasonography (inclu...
Overview of Eye Disorders in Children
Apr 16, 2006
Congenital glaucoma and congenital cataracts (see ) are uncommon disorders that can affect newborns and young children. Disorders that most often blur vision, such as nearsightedness, farsightedness, and astigmatism (all considered refractive errors)...
Amblyopia
Apr 16, 2006
Amblyopia, a common cause of vision loss in children, is a decrease in vision that occurs because the brain ignores the image received from one eye. Vision loss may be irreversible if not diagnosed and treated before age 8.
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Strabismus
Apr 16, 2006
Strabismus (also called squint, cross-eye, lazy eye, or wandering eye) is an intermittent or constant misalignment of an eye so that its line of vision is not pointed at the same object as the other eye. If untreated, strabismus can cause am...
Overview of Heart Tumors
Mar 23, 2006
A tumor is any type of abnormal growth, whether cancerous (malignant) or noncancerous (benign). Tumors that originate in the heart are called primary tumors. They may develop in any of the heart tissues and may be cancerous or noncancerous. Primary h...
Myxomas
Mar 23, 2006
A myxoma is a noncancerous primary tumor, usually irregular in shape and jellylike in consistency.
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Cancerous Tumors
Mar 23, 2006
Cancerous primary heart tumors are extremely rare, accounting for about one fourth of primary heart tumors. The most common are sarcomas that develop from blood vessel tissue. Secondary heart tumors are far more common, but how common is difficult to...
Biology of the Mouth
Mar 14, 2006
The mouth is the entrance to both the digestive and the respiratory systems. The inside of the mouth is lined with mucous membranes. When healthy, the lining of the mouth (oral mucosa) is reddish pink; the gums are paler pink and fit snugly around th...
Effects of Aging on the Mouth
Mar 14, 2006
With aging, the taste buds become less sensitive, so older people may add abundant seasonings (particularly salt) or may find their food tastes bland. Older people may also have disorders or take drugs that affect their ability to taste. Such disorde...
Ears
Mar 10, 2006
The ear, which is the organ of hearing and balance, consists of the outer, middle, and inner ear. The outer, middle, and inner ear function together to convert sound waves into nerve impulses that travel to the brain, where they are perceived as soun...
Nose and Sinuses
Mar 10, 2006
The nose is the organ of smell and a main passageway for air into and out of the lungs. The nose warms, moistens, and cleans air before it enters the lungs. The bones of the face around the nose contain hollow spaces called paranasal sinuses. There a...
Throat
Mar 10, 2006
The throat (pharynx) is located behind the mouth, below the nasal cavity, and above the esophagus and windpipe (trachea). It consists of an upper part (nasopharynx), a middle part (oropharynx), and a lower part (hypopharynx). The throat is a muscular...
Effects of Aging on the Ears, Nose, and Throat
Mar 10, 2006
Aging greatly affects the function of the ears, nose, and throat. The effects of aging result from many factors such as wear and tear, noise, and the cumulative effect of infections, as well as the effect of substances such as drugs, alcohol, and tob...
Heart
Feb 24, 2006
The heart, a hollow muscular organ, is located in the center of the chest. The right and left sides of the heart each have an upper chamber (atrium), which collects blood and pumps it into a lower chamber (ventricle), which pumps blood out....
Blood Vessels
Feb 24, 2006
The blood vessels consist of arteries, arterioles, capillaries, venules, and veins. All blood is carried in these vessels. The arteries, which are strong, flexible, and resilient, carry blood away from the heart and bear the highest blood pressures. ...
Effects of Aging on the Heart and Blood Vessels
Feb 24, 2006
As people age, the heart tends to enlarge slightly, developing thicker walls and slightly larger chambers. The increase in size is mainly due to an increase in the size of individual heart muscle cells....
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