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

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.

See also:

• Anemia due to B12 deficiency
• Anemia due to folate deficiency
• Anemia due to iron deficiency
• Hemolytic anemia
• Hemolytic anemia due to G-6-PD deficiency
• Idiopathic aplastic anemia
• Idiopathic autoimmune hemolytic anemia
• Immune hemolytic anemia
• Megaloblastic anemia
• Pernicious anemia
• Secondary aplastic anemia
• Sickle cell anemia

The cause depends on the type of anemia. Possible causes include:

• Certain medications
• Diseases such as cancer or rheumatoid arthritis
• Genes -- some forms of anemia can be inherited
• Kidney failure
• Blood loss (for example, from heavy menstrual periods)
• Poor diet
• Pregnancy
• Problems with bone marrow (where blood cells are made)
• Problems with the immune system that cause the destruction of blood cells
• 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.

The following blood tests are used to diagnose anemia:

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

Antony AC. Megaloblastic anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 170.

Zuckerman KS. Approach to the anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 162.