Not all chronic diseases involve the inflammatory process and anemia. For example, high blood pressure is a chronic disease, but it does not affect red blood cells.
Treatment-related anemia results from the therapies used to treat conditions. For example, anemia is a common side effect of cancer treatments. Chemotherapy and radiation can impair the bone marrow's production of red blood cells and contribute to the extreme fatigue that many patients experience during cancer therapy. Patients with hepatitis C frequently receive combination therapy of ribavirin and interferon; ribavirin can induce anemia. Hepatitis C also affects many patients with HIV or AIDS. In addition to ribavirin, patients with HIV or AIDS can develop anemia as a result of highly active anti-retroviral therapy (HAART) and, in particular, from the drug AZT.
Other medications that increase the risk for anemia are certain antibiotics, some antiseizure medications (phenytoin), immunosuppressive drugs (methotrexate, azathioprine), antiarrhythmic drugs (procainamide, quinidine), and anti-clotting drugs (aspirin, warfarin, clopidogrel, heparin).
Megaloblastic anemia results from deficiencies in the B vitamins folate or vitamin B12 (also called cobalamin). Such deficiencies produce abnormally large (megaloblastic) red blood cells that have a shortened lifespan. Neurologic problems may be associated with vitamin B12 deficiency.
|Click the icon to see an image of red blood cells seen in megaloblastic anemia.|
Causes of Vitamin B12 Deficiency. Conditions that cause vitamin B12 deficiencies include:
- Vitamin B12 deficiency from diet is very rare, because the liver stores over a 3-year supply. It usually does not occur even in alcoholism, strict vegetarianism, or in malnourished people with kidney failure or cancer. Since animal products are the chief source, however, true vegan vegetarians may need a supplement, fortified food, or appropriate food selection known to contain adequate amounts of this vitamin
- Pernicious anemia. Pernicious anemia is an autoimmune disease in which antibodies are tricked into attacking stomach cells. This results in impaired production of intrinsic factor (IF), a compound that is critical for absorption of vitamin B12. Pernicious anemia is diagnosed in about 1% of people over age 60, with women having a higher risk than men.
- Complications of gastrointestinal surgery. Surgeries such as stomach bypass or stapling, which remove part or all of the stomach, pose a risk of causing vitamin B12 deficiencies.
- Overgrowth of intestinal bacteria
- Tropical sprue (an acquired malabsorption disease occurring in tropical climates)
Review Date: 01/13/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.