When blood loss is rapid, blood pressure falls, and people may be dizzy.
When blood loss occurs gradually, people may be tired, short of breath, and pale.
Stool, urine, and imaging tests may be needed to determine the source of bleeding.
The cause of bleeding is corrected, and transfusions and iron supplements are given if needed.
The most common cause of 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 is
When blood is lost, the body quickly pulls water from tissues outside the bloodstream in an attempt to keep the blood vessels filled. As a result, the blood is diluted, and the hematocrit (the percentage of red blood cells in the total amount of blood in the body, or blood volume) is reduced. Eventually, increased production of red blood cells by the bone marrow may correct the anemia. However, over time, bleeding reduces the amount of iron in the body, so that the bone marrow is not able to increase production of new red blood cells to replace those lost.
Rapid blood loss
The symptoms may be severe initially, especially if anemia develops rapidly as a result of the sudden loss of blood due to an injury, surgery, childbirth, or a ruptured blood vessel. Losing large amounts of blood suddenly can create two problems:
Blood pressure falls Low Blood Pressure Low blood pressure is blood pressure low enough to cause symptoms such as dizziness and fainting. Very low blood pressure can cause damage to organs, a process called shock. Various drugs and... read more because the amount of fluid left in the blood vessels is insufficient.
The body’s oxygen supply is drastically reduced because the number of oxygen-carrying red blood cells has decreased so quickly.
Either problem may lead to a heart attack Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) 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... read more , stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more , or death.
Chronic blood loss
Far more common than a sudden loss of blood is long-term (chronic) bleeding, which may occur from various parts of the body. Although large amounts of bleeding, such as that from nosebleeds and hemorrhoids, are obvious, small amounts of bleeding may not be noticed. For example, a small amount of blood may not be visible in the stool. This type of blood loss is described as occult (hidden). If a small amount of bleeding continues for a long time, a significant amount of blood may be lost. Such gradual bleeding may occur with common disorders, such as ulcers Peptic Ulcer Disease 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. Peptic ulcers can result from Helicobacter pylori... read more in the stomach or small intestine, diverticulosis Diverticulosis of the Large Intestine Diverticulosis is the presence of one or more balloon-like sacs (diverticula), usually in the large intestine (colon). The cause of diverticulosis is unknown but may be related to diet, a sedentary... read more , polyps Polyps of the Colon and Rectum A polyp is a projecting growth of tissue from the wall of a hollow space, such as the intestines. Some polyps are caused by hereditary conditions. Bleeding from the rectum is the most common... read more in the large intestine, or cancers in the large intestine Colorectal Cancer Family history and some dietary factors (low fiber, high fat) increase a person’s risk of colorectal cancer. Typical symptoms include bleeding during a bowel movement, fatigue, and weakness... read more . Other sources of chronic bleeding include kidney tumors Kidney Cancer Kidney cancer may cause blood in the urine, pain in the side, or fever. Cancer is most often detected by accident when an imaging test is done for another reason. Diagnosis is by computed tomography... read more or bladder tumors Bladder Cancer Bladder cancer most often causes blood in the urine. To make the diagnosis, a thin, flexible viewing tube (cystoscope) is inserted through the urethra into the bladder. Many cancers are treated... read more , which may cause blood to be lost in the urine, and heavy menstrual bleeding Abnormal Uterine Bleeding (AUB) Abnormal uterine bleeding is bleeding from the vagina that occurs frequently or irregularly or lasts longer or is heavier than normal menstrual periods. The most common type of abnormal bleeding... read more .
Symptoms are similar to those of other types of anemia and vary from mild to severe, depending on
How much blood is lost
How rapidly blood is lost
When the blood loss is rapid—over several hours or less—loss of just one third of the blood volume can be fatal. Dizziness upon sitting or standing after a period of lying down (orthostatic hypotension) is common when blood loss is rapid. When the blood loss is slower—over several weeks or longer—loss of up to two thirds of the blood volume may cause only fatigue and weakness or no symptoms at all, if the person drinks enough fluids.
Other symptoms may occur as a result of the bleeding or the disorder that causes the bleeding. People may notice black, tarry stools if they have bleeding from the stomach or small intestine. Bleeding from the kidneys or bladder may cause red or brown urine. Women may notice long, heavy menstrual periods. Some disorders that cause chronic bleeding, such as stomach ulcers, cause abdominal discomfort. Other disorders, such as diverticulosis and intestinal cancers and polyps at an early stage, cause no symptoms.
Sometimes imaging or endoscopy
Doctors do blood tests to detect anemia when people describe symptoms of anemia, have noticed bleeding, or both. Stool and urine are tested for blood in an effort to identify the source of bleeding.
Imaging tests or endoscopy may be needed to identify the source of bleeding.
Usually iron supplements
For large or rapid blood loss, the source of bleeding must be found and the bleeding stopped. Transfusion of red blood cells Red blood cells People are sometimes given transfusions of whole blood during severe bleeding (for example after an injury or pregnancy complications), but usually they are given only the blood component they... read more may be needed.
With slow or small blood loss, the body may produce enough red blood cells to correct the anemia without the need for blood transfusions when the bleeding is stopped.
Because iron, which is required to produce red blood cells, is lost as a result of bleeding, most people who have anemia due to bleeding need to take iron supplements, usually tablets, for several months. Sometimes they are given iron intravenously.