Anemia From Excessive Bleeding
Anemia from excessive bleeding results when loss of red blood cells through bleeding exceeds production of new red blood cells.
Excessive bleeding is the most common cause of anemia. 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 blood volume) is reduced. Eventually, increased production of red blood cells may correct the anemia. Over time, bleeding can reduce 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.
The symptoms may be severe initially, especially if anemia develops rapidly from a sudden loss of blood, such as from an accident, surgery, childbirth, or a ruptured blood vessel. Losing large amounts of blood suddenly can create two problems: Blood pressure falls because the amount of fluid left in the blood vessels is insufficient, and the body's oxygen supply is drastically reduced because the number of oxygen-carrying red blood cells has diminished so quickly. Either problem may lead to a heart attack, stroke, or death.
Far more common than a sudden loss of blood is chronic (continuous or repeated) bleeding, which may occur in various parts of the body. Bleeding from nosebleeds and hemorrhoids is obvious. Bleeding from other common sources--such as ulcers in the stomach or small intestine and polyps or cancers in the large intestine--may not be obvious. The amount of blood is small and may not be visible in the stool. This type of blood loss is described as occult. Other sources of chronic bleeding include kidney or bladder tumors, which may cause blood to be lost in the urine, and heavy menstrual bleeding.
Symptoms and Diagnosis
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 the blood is lost also determines whether symptoms are mild or severe. 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 days, 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.
A doctor may suspect blood loss is causing anemia when a person describes symptoms of anemia and has noticed bleeding. 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.
Treatment
For large or rapid blood loss, transfusion of red blood cells is the only reliable treatment. Also, the source of bleeding must be found and stopped. With slow or small blood loss, the body may produce enough red blood cells to correct the anemia without the need for blood transfusions. Because iron, which is required to produce red blood cells, is lost during bleeding, most people who have anemia from bleeding need to take iron supplements, usually tablets, for several months.
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