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

While many parts of the body are essential to making 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 signal 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
• Genes -- some forms of anemia, such as thalassemia, can be inherited
• Kidney failure
• Blood loss (for example, from heavy menstrual periods or stomach ulcers)
• Poor diet
• Pregnancy
• 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

Possible symptoms include:

• Chest pain
• Dizziness or light-headedness (especially when standing up or with exertion)
• Fatigue or lack of energy
• Headaches
• Problems concentrating
• Shortness of breath (especially during exercise)

Some types of anemia may have other symptoms, such as:

• Constipation
• Problems thinking
• Tingling

The doctor will perform a physical examination, and may find:

• Pale skin
• Rapid heart rate

Some types of anemia may cause other findings on a physical exam.

Blood tests used to diagnose some common types of anemia may include:

• Blood levels of vitamin B12, folic acid, and other vitamins and minerals
• Bone marrow examination
• Red blood count and hemoglobin level
• Reticulocyte count
• Ferritin level
• Iron level

Other tests may be done to identify medical problems that can cause anemia.

Treatment should be directed at the cause of the anemia, and may include:

• Blood transfusions
• Corticosteroids or other medicines that suppress the immune system
• Erythropoietin, a medicine that helps your bone marrow make more blood cells
• Supplements of iron, vitamin B12, folic acid, or other vitamins and minerals

The outlook depends on the cause.

Severe anemia can cause low oxygen levels in vital organs such as the heart, and can lead to a heart attack.

Call your health provider if you have any symptoms of anemia, or any unusual bleeding.

Marks PW, Glader B. Approach to anemia in the adult and child. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 34.