Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.
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
While 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.
Possible causes of anemia include:
- Certain medications
- Chronic diseases such as cancer, ulcerative colitis, or rheumatoid arthritis
- Genetis: Some forms of anemia, such as thalassemia, can be inherited
- Blood loss (for example, from heavy menstrual periods or
- Poor diet
- Problems with bone marrow such as lymphoma, leukemia, or multiple myeloma
- Problems with the immune system that cause the destruction of blood cells (hemolytic anemia)
- Surgery to the stomach or intestines that reduces the absorption of iron, vitamin B12, or folic acid
- Too little thyroid hormone (underactive thyroid, or hypothyroidism)
- Testosterone deficiency
Review Date: 02/28/2011
Reviewed By: David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital.