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Anemia Due to Excessive Bleeding


Evan M. Braunstein

, MD, PhD, Johns Hopkins University School of Medicine

Reviewed/Revised Jul 2022 | Modified Sep 2022

Anemia due to excessive bleeding results when loss of red blood cells exceeds production of new red blood cells.

  • 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.

  • Excessive bleeding

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

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 infection with Helicobacter... read more Peptic Ulcer Disease in the stomach or small intestine, polyps Polyps of the Colon and Rectum A polyp is a growth of tissue that projects 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 Polyps of the Colon and Rectum 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 Colorectal Cancer . Other sources of chronic bleeding include kidney tumors Kidney Cancer Most solid kidney tumors are cancerous, but purely fluid-filled tumors (cysts) generally are not. Almost all kidney cancer is renal cell carcinoma. Another kind of kidney cancer, Wilms tumor... read more or bladder tumors Bladder Cancer Most bladder cancers arise from the cells that form the innermost layer of the bladder. These cells, called transitional cells or urothelial cells, allow the bladder to stretch when it is full... read more , which may cause blood to be lost in the urine, and heavy menstrual bleeding Abnormal Uterine Bleeding (AUB) Abnormal uterine bleeding in women of childbearing age is bleeding from the uterus that does not follow the normal pattern for menstrual cycles. That is, it occurs too frequently or irregularly... read more Abnormal Uterine Bleeding (AUB) .


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 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 Diverticulosis of the Large Intestine and intestinal cancers and polyps at an early stage, cause no symptoms.


  • Blood tests

  • 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.


  • Stopping bleeding

  • Usually iron supplements

With slow or small blood loss, the body may produce enough red blood cells to correct the anemia without the need for blood transfusions once 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 people are given iron intravenously.

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