Anemia


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Definition

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.

See also:

  • Anemia due to B12 deficiency
  • Anemia due to folate deficiency
  • Anemia due to iron deficiency
  • Anemia of chronic disease
  • Hemolytic anemia
  • Idiopathic aplastic anemia
  • Megaloblastic anemia
  • Pernicious anemia
  • Secondary aplastic anemia
  • Sickle cell anemia
  • Thalassemia

Causes, incidence, and risk factors

Although many parts of the body help make red blood cells, most of the work is done in the bone marrow. Bone marrow is the soft tissue in the center of bones that helps form blood cells.

Healthy red blood cells last between 90 and 120 days. Parts of your body then remove old blood cells. A hormone called erythropoietin made in your kidneys signals your bone marrow to make more red blood cells.

Hemoglobin is the oxygen-carrying protein inside red blood cells. It gives red blood cells their red color. People with anemia do not have enough hemoglobin.

The body needs certain vitamins, minerals, and nutrients to make enough red blood cells. Iron, vitamin B12, and folic acid are three of the most important ones. The body may not have enough of these nutrients because:

  • Changes in the lining of the stomach or intestines affect how well nutrients are absorbed (for example, celiac disease)
  • Poor diet
  • Slow blood loss (for example, from heavy menstrual periods or stomach ulcers)
  • Surgery that removes part of the stomach or intestines

Possible causes of anemia include:

  • Certain medications
  • Destruction of red blood cells earlier than normal (which may be caused by immune system problems)
  • Long-term (chronic) diseases such as chronic kidney disease, cancer, ulcerative colitis, or rheumatoid arthritis
  • Some forms of anemia, such as thalassemia or sickle cell anemia, which can be inherited
  • Pregnancy
  • Problems with bone marrow such as lymphoma, leukemia, multiple myeloma, or aplastic anemia

References

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 161.


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Review Date: 2/7/2012
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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Last Updated 4/24/2012
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