Medications and disorders that damage the kidneys may cause nephrotic syndrome.
People feel tired and have tissue swelling (edema).
Diagnosis is based on blood and urine tests and sometimes imaging of the kidneys, a biopsy of the kidneys, or both.
People who have disorders that may cause nephrotic syndrome are given angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) to slow kidney damage.
Restriction of sodium intake plus diuretics and statins are also used to treat this disorder.
(See also Overview of Kidney Filtering Disorders Overview of Kidney Filtering Disorders 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... read more .)
Nephrotic syndrome can develop gradually or suddenly. Nephrotic syndrome can occur at any age. In children, it is most common between the ages of 18 months and 4 years, and more males than females are affected. In older people, both sexes are equally affected.
Excessive protein excretion into the urine (proteinuria) results in low levels of important proteins, such as albumin, in the blood. People also have increased levels of fats (lipids) in the blood, a tendency to increased blood clotting Excessive Clotting Excessive clotting (thrombophilia) occurs when the blood clots too easily or excessively. Inherited and acquired disorders can increase blood clotting. Clots in larger blood vessels cause legs... read more , and a greater susceptibility to infection. The decreased level of albumin in the blood causes fluid to leave the bloodstream and enter the tissues. Fluid in the tissues leads to edema Swelling Swelling is due to excess fluid in the tissues. The fluid is predominantly water. Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and... read more . Fluid leaving the bloodstream causes the kidneys to compensate by retaining more sodium.
Causes of Nephrotic Syndrome
Nephrotic syndrome can be
Primary, originating in the kidneys
Secondary, caused by a vast array of other disorders
A variety of primary kidney disorders can damage the glomeruli and cause nephrotic syndrome. Minimal change disease is the most common cause of nephrotic syndrome in children.
The secondary causes may involve other parts of the body. The most common disorders causing nephrotic syndrome are diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Symptoms of diabetes may... read more , systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more (lupus), and certain viral infections. Nephrotic syndrome can also result from kidney inflammation (glomerulonephritis Glomerulonephritis Glomerulonephritis 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... read more ). A number of medications that are toxic to the kidneys can also cause nephrotic syndrome, especially nonsteroidal anti-inflammatory drugs Nonsteroidal Anti-Inflammatory Drugs Pain relievers (analgesics) are the main drugs used to treat pain. Doctors choose a pain reliever based on the type and duration of pain and on the drug's likely benefits and risks. Most pain... read more (NSAIDs). The syndrome may be caused by certain allergies, including allergies to insect bites and to poison ivy or poison oak. Some types of nephrotic syndrome are hereditary.
Symptoms of Nephrotic Syndrome
Early symptoms include
Loss of appetite
A general feeling of illness (malaise)
Puffy eyelids and tissue swelling (edema) due to excess sodium and water retention
The abdomen may be swollen because of a large accumulation of fluid in the abdominal cavity (ascites Ascites Ascites is the accumulation of protein-containing (ascitic) fluid within the abdomen. Many disorders can cause ascites, but the most common is high blood pressure in the veins that bring blood... read more ). Shortness of breath may develop because fluid accumulates in the space surrounding the lungs (pleural effusion Pleural Effusion Pleural effusion is the abnormal accumulation of fluid in the pleural space (the area between the two layers of the thin membrane that covers the lungs). Fluid can accumulate in the pleural... read more ). Other symptoms may include swelling of the labia or scrotum. Most often, the fluid that causes tissue swelling is affected by gravity and therefore moves around. During the night, fluid accumulates in the upper parts of the body, such as the eyelids. During the day, when the person is sitting or standing, fluid accumulates in the lower parts of the body, such as the ankles. Swelling may hide the muscle wasting that is progressing at the same time.
In children, blood pressure is generally low, and blood pressure may fall when the child stands up (orthostatic or postural hypotension) Dizziness or Light-Headedness When Standing Up In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness... read more . Shock Shock Shock is a life-threatening condition in which blood flow to the organs is low, decreasing delivery of oxygen and thus causing organ damage and sometimes death. Blood pressure is usually low... read more occasionally develops. Adults may have low, normal, or high blood pressure.
Urine production may decrease, and kidney failure Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more (loss of most kidney function) may develop if the leakage of fluid from blood vessels into tissues depletes the liquid component of blood and the blood supply to the kidneys is diminished. Occasionally, kidney failure with low urine output occurs suddenly.
Nutritional deficiencies may result because nutrients are excreted in the urine. In children, growth may be stunted. Calcium may be lost from bones, and people may have a vitamin D deficiency, Vitamin D Deficiency Vitamin D deficiency is most commonly caused by a lack of exposure to sunlight. Some disorders can also cause the deficiency. The most common cause is lack of exposure to sunlight, usually when... read more leading to osteoporosis. Osteoporosis Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more The hair and nails may become brittle, and some hair may fall out. Horizontal white lines may develop in fingernail beds for unknown reasons.
The membrane that lines the abdominal cavity and abdominal organs (peritoneum) may become inflamed and infected. Opportunistic infections—infections caused by normally harmless bacteria—are common. The higher likelihood of infection is thought to occur because the antibodies that normally combat infections are excreted in the urine or not produced in normal amounts. The tendency for blood clotting Excessive Clotting Excessive clotting (thrombophilia) occurs when the blood clots too easily or excessively. Inherited and acquired disorders can increase blood clotting. Clots in larger blood vessels cause legs... read more (thrombosis) increases, particularly inside the main veins draining blood from the kidneys. Less commonly, the blood may not clot when clotting is needed, generally leading to excessive bleeding. High blood pressure accompanied by complications affecting the heart and brain is most likely to occur in people who have diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Symptoms of diabetes may... read more or systemic lupus erythematosus. Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more
Diagnosis of Nephrotic Syndrome
Urine and blood tests
A doctor bases the diagnosis of nephrotic syndrome on symptoms, physical examination findings, and laboratory findings. Sometimes nephrotic syndrome is at first mistaken for heart failure in older adults because swelling occurs in both disorders and heart failure is common among older people.
A laboratory test of urine collected over a 24-hour period is useful for measuring the degree of protein loss, but collection of urine over such a long period is difficult for many people to accomplish. Alternatively, to estimate protein loss, a single urine specimen can be tested to measure the ratio of the level of protein to that of creatinine (a waste product).
Blood tests and other urine tests detect additional characteristics of the syndrome. The level of albumin in the blood is low because this vital protein is excreted in the urine and its production is impaired. The urine often contains clumps of cells that may be combined with protein and fat (casts). The urine contains low levels of sodium and high levels of potassium.
Concentrations of lipid in the blood are high, sometimes exceeding 10 times that of a normal concentration. Levels of lipid in the urine are also high. Anemia Overview of Anemia Anemia is a condition in which the number of red blood cells is low. Red blood cells contain hemoglobin, a protein that enables them to carry oxygen from the lungs and deliver it to all parts... read more may be present. Levels of blood clotting proteins may be increased or decreased.
Determining the cause of nephrotic syndrome
The doctor investigates possible causes of nephrotic syndrome, including medications or illicit drugs.
Analysis of the urine and blood may reveal an underlying disorder. For example, the blood is tested for evidence of previous infections that could cause nephrotic syndrome and for antibodies directed against the body's own tissues (called autoantibodies), which indicate an autoimmune disorder Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more .
An imaging test of the kidneys Imaging Tests of the Urinary Tract There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more , such as ultrasonography or computed tomography (CT), may be done. If the person has lost weight or is older, a search for cancer is undertaken. A kidney biopsy is especially useful in determining the cause and extent of kidney damage.
Treatment of Nephrotic Syndrome
Treatment of the cause
Dietary management and other measures
Treatment of the cause of nephrotic syndrome
Whenever possible, specific treatment is aimed at the cause. Treating an infection that causes nephrotic syndrome may cure the syndrome. If a treatable disease, such as certain cancers, causes nephrotic syndrome, treating that disease can eliminate the syndrome.
If a heroin user with nephrotic syndrome stops using heroin in the early stages of the disease, the syndrome may resolve. If other medications or illicit drugs are responsible for the syndrome, stopping these may be curative.
People who are sensitive or allergic to poison oak, poison ivy, or insect bites should avoid these irritants.
When a person who already has nephrotic syndrome is treated with an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin II receptor blocker (ARB), symptoms may decrease, the amount of protein excreted in the urine usually decreases, and fat concentrations in the blood are likely to decline. However, these medications can increase the potassium levels in the blood in people who have moderate to severe kidney failure Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more , which can cause potentially dangerous heart rhythm abnormalities Overview of Abnormal Heart Rhythms 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. Heart disorders are... read more .
Anticoagulants may help control clot formation if it occurs. Infections can be life threatening and must be treated promptly.
Statins, medications that lower the amount of cholesterol in the blood, may also be needed if people have increased levels of fats (lipids) in the blood.
If no reversible cause can be found, the person may be given corticosteroids and other medications that suppress the immune system, such as cyclophosphamide. However, corticosteroids cause problems, particularly for children, in whom these medications can stunt growth and suppress sexual development (see sidebar ).
Dietary management and other measures
General therapy for nephrotic syndrome includes a diet that contains normal amounts of protein and potassium but that is low in saturated fat, cholesterol, and sodium.
If fluid accumulates in the abdomen, the person may need to eat frequent, small meals because the fluid reduces the capacity of the stomach.
People should receive the pneumococcal vaccine Pneumococcal Vaccine Pneumococcal vaccines help protect against bacterial infections caused by Streptococcus pneumoniae (pneumococci). Pneumococcal infections include ear infections, sinusitis, pneumonia... read more .
Rarely, so much protein is lost in the urine that the kidneys must be removed.
Prognosis for Nephrotic Syndrome
The prognosis varies depending on the
Cause of the nephrotic syndrome
Type of kidney damage
Degree of kidney damage
Symptoms may disappear completely if the nephrotic syndrome is caused by a treatable disorder, such as an infection, cancer, or medications, provided the condition is treated early and effectively. This situation occurs in about half the cases in children but less often in adults. If the underlying disorder responds to corticosteroids, sometimes progression of the disease is halted, and less often the condition partially or, rarely, completely reverses. When the syndrome is caused by human immunodeficiency virus (HIV) infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more , it usually progresses relentlessly, often resulting in complete kidney failure in 3 or 4 months. Children born with nephrotic syndrome rarely live beyond their first birthday, although a few have survived by means of dialysis Dialysis 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. There are a number of reasons... read more treatments or a kidney transplant. Kidney Transplantation Kidney transplantation is the removal of a healthy kidney from a living or recently deceased person and then its transfer into a person with end-stage kidney failure. (See also Overview of Transplantation... read more
When the cause is systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more or diabetes mellitus, Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Symptoms of diabetes may... read more medications often stabilize or decrease the amount of protein in the urine. However, some people do not respond to medications and develop chronic kidney disease Chronic Kidney Disease Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood. Major causes are diabetes and high blood pressure... read more , which then progresses to kidney failure within a few years.
Prevention of Nephrotic Syndrome
Use of an angiotensin-converting enzyme (ACE) inhibitor, such as enalapril, benazepril, or lisinopril, or an angiotensin II receptor blocker (ARB), such as candesartan, losartan, or valsartan, is the mainstay of both prevention and treatment. When a person with a disease such as systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more or diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Symptoms of diabetes may... read more has mild or moderate proteinuria, an ACE inhibitor or ARB is used as soon as possible because the medication may prevent proteinuria from increasing and kidney function from worsening.
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Kidney Fund, Nephrotic Syndrome: General information on nephrotic sydrome, including answers to frequently asked questions
Drugs Mentioned In This Article
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|Calcidol, Calciferol, D3 Vitamin, DECARA, Deltalin, Dialyvite Vitamin D, Dialyvite Vitamin D3, Drisdol, D-Vita, Enfamil D-Vi-Sol, Ergo D, Fiber with Vitamin D3 Gummies Gluten-Free, Happy Sunshine Vitamin D3, MAXIMUM D3, PureMark Naturals Vitamin D, Replesta, Replesta Children's, Super Happy SUNSHINE Vitamin D3, Thera-D 2000, Thera-D 4000, Thera-D Rapid Repletion, THERA-D SPORT, UpSpring Baby Vitamin D, UpSpring Baby Vitamin D3, YumVs, YumVs Kids ZERO, YumVs ZERO
|Cyclophosphamide, Cytoxan, Neosar
|Prinivil, QBRELIS, Zestril