Many medical conditions cause anemia. Common causes of anemia include the following:
Anemia from active bleeding: Loss of blood through heavy menstrual bleeding or wounds can cause anemia. Gastrointestinal ulcers or cancers such as cancer of the colon may slowly ooze blood and can also cause anemia.
Iron deficiency anemia: The bone marrow needs iron to make red blood cells. Iron (Fe) plays an important role in the proper structure of the hemoglobin molecule. If iron intake is limited or inadequate due to poor dietary intake, anemia may occur as a result. This is called iron deficiency anemia. Iron deficiency anemia can also occur when there are stomach ulcers or other sources of slow, chronic bleeding (colon cancer, uterine cancer, intestinal polyps, hemorrhoids, etc). In these kinds of scenarios, because of ongoing, chronic slow blood loss, iron is also lost from the body (as a part of blood) at a higher rate than normal and can result in iron deficiency anemia.
Anemia of chronic disease: Any long-term medical condition can lead to anemia. The exact mechanism of this process in unknown, but any long-standing and ongoing medical condition such as a chronic infection or a cancer may cause this type of anemia.
Anemia related to kidney disease: The kidneys release a hormone called the erythropoietin that helps the bone marrow make red blood cells. In people with chronic (long-standing) kidney disease (CKD or end stage renal disease (ESRD), the production of this hormone is diminished, and this, in turn, diminishes the production of red blood cells, causing anemia. This is called anemia related to or anemia of chronic kidney disease.
Anemia related to pregnancy: Water weight and fluid gain during pregnancy dilutes the blood, which may be reflected as anemia since the relative concentration of red blood cells is lower.
Anemia related to poor nutrition: Vitamins and minerals are required to make red blood cells. In addition to iron, vitamin B12 and folate (or folic acid) are required for the proper production of hemoglobin (Hgb). Deficiency in any of these may cause anemia because of inadequate production of red blood cells. Poor dietary intake is an important cause of low folate and low vitamin B12 levels. Strict vegetarians who do not take sufficient vitamins are at risk to develop vitamin B12 deficiency.
Pernicious anemia: There also may be a problem in the stomach or the intestines leading to poor absorption of vitamin B12. This may lead to anemia because of vitamin B12 deficiency known as pernicious anemia.
Sickle cell anemia: In some individuals, the problem may be related to production of abnormal hemoglobin molecules. In this condition, the hemoglobin problem is qualitative, or functional. Abnormal hemoglobin molecules may cause problems in the integrity of the red blood cell structure and they may become crescent-shaped (sickle cells). There are different types of sickle cell anemia with different severity levels. This is typically hereditary and is more common in those of African, Middle Eastern, and Mediterranean ancestry. People with sickle cell anemia can be diagnosed as early as childhood depending on the severity and symptoms of their disease.
Medically Reviewed by a Doctor on 11/11/2014
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