Causes of anemia

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 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, 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 chronic kidney disease.
• Anemia related to pregnancy: Water weight gain during pregnancy dilutes the blood, which may be reflected as anemia.
• Anemia related to poor nutrition: Vitamins and minerals are required to make red blood cells. In addition to iron, vitamin B12 and folate are required for the proper production of hemoglobin. 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 call anemia with different severity levels. This is typically hereditary and is more common in those of African, Middle Eastern, and Mediterranean ancestry.
• Thalassemia: This is another group of hemoglobin-related causes of anemia. There are many types of thalassemia, which vary in severity from mild (thalassemia minor) to severe (thalassemia major). These are also hereditary, but they cause quantitative hemoglobin abnormalities, meaning an insufficient amount of the correct hemoglobin type molecules is made. Thalassemia is more common in people from African, Mediterranean, and Southeast Asian ancestries.
• Alcoholism: Poor nutrition and deficiencies of vitamins and minerals are associated with alcoholism. Alcohol itself may also be toxic to the bone marrow and may slow down the red blood cell production. The combination of these factors may lead to anemia in alcoholics.
• Bone marrow-related anemia: Anemia may be related to diseases involving the bone marrow. Some blood cancers such as leukemia or lymphomas can alter the production of red blood cells and result in anemia. Other processes may be related to a cancer from another organ spreading to the bone marrow.
• Aplastic anemia: Occasionally some viral infections may severely affect the bone marrow and significantly diminish production of all blood cells. Chemotherapy (cancer medications) and some other medications may pose the same problems.
• Hemolytic anemia: The normal red blood cell shape is important for its function. Hemolytic anemia is a type of anemia in which the red blood cells rupture (known as hemolysis) and become dysfunctional. This could happen due to a variety of reasons. Some forms of hemolytic anemia can be hereditary with constant destruction and rapid reproduction of red blood cells (for example, as in hereditary spherocytosis, hereditary elliptocytosis, and glucose-6-phosphate dehydrogenase or G6GD deficiency) . This type of destruction may also happen to normal red blood cells in certain conditions, for example, with abnormal heart valves damaging the blood cells or certain medications that disrupt the red blood cell structure.
• Anemia related to medications: Many common medications can occasionally cause anemia as a side effect in some individuals. The mechanisms by which medications can cause anemia are numerous (hemolysis, bone marrow toxicity) and are specific to the medication. Medications that most frequently cause anemia are chemotherapy drugs used to treat cancers. Other common medications that can cause anemia include some seizure medications, transplant medications, HIV medications, some malaria medications, some antibiotics (penicillin, chloramphenicol), antifungal medications, and antihistamines.
• Other less common causes of anemia include thyroid problems, cancers, liver disease, autoimmune diseases (lupus), paroxysmal nocturnal hemoglobinuria (PNH), lead poisoning, AIDS, malaria, viral hepatitis, mononucleosis, parasitic infections (hookworm), bleeding disorders, and insecticide exposure. It is noteworthy that there are many other potential causes of anemia that are not included in this list as these are only some of the more common and important ones.

Important factors to remember are:

• Certain forms of anemia are hereditary and infants may be affected from the time of birth.
• Women in the childbearing years are particularly susceptible to a form of anemia called iron-deficiency anemia because of the blood loss from menstruation and the increased blood supply demands during pregnancy.

Seniors also may have a greater risk of developing anemia because of poor diet and other medical conditions.