Anemia is the most common disorder of the blood. Anemia is a lower than normal number of red blood cells in the blood. Red blood cells carry oxygen to tissues on a protein called hemoglobin. A deficiency of red blood cells results in a decreased ability to transfer oxygen from the blood to tissues. There are many different types and causes of anemia. Some causes of anemia include blood loss, nutritional deficiencies, diseases, reactions to medications, and problems with bone marrow. The three main classes of anemia are those due to excessive blood loss, excessive red blood cell destruction, or deficient red blood cell production.

The symptoms of anemia can be vague and may go undetected in many cases. The most common symptom reported is weakness or fatigue. Shortness of breath can be a sign of severe anemia. Very severe anemia causes the heart to compensate with increased cardiac output resulting in palpitations and heart failure. The only way to diagnose anemia is with a blood test. Most often a whole blood count is used. A whole blood count measures the number of red blood cells, the amount of hemoglobin, and the size of red blood cells in whole blood.

Iron deficiency anemia is the most common type of anemia. Iron is an essential component of hemoglobin. Iron deficiency occurs when dietary intake or absorption of iron are inadequate. Iron deficiency is the most common deficiency disorder worldwide. Iron from red meat is more easily absorbed by the body than non-meat forms. Areas of the world with low red meat consumption have 6 to 8 times the incidence of iron deficiency anemia than the US or Europe. Iron deficiency anemia is most common in premenopausal women in the US—20% of women of childbearing age in the US have iron deficiency anemia compared to only 2% of men. The primary cause of iron deficiency anemia in premenopausal women in the US is blood loss during menstruation.

Deficiencies of vitamin B12 or folic acid or both cause megaloblastic anemia. Vitamin B12 deficiency also results in disorders of the nerves, while folic acid deficiency does not. A related form of anemia called pernicious anemia results from an autoimmune condition that destroys the parietal cells of the lining of the stomach. Parietal cells are responsible for the absorption of vitamin B12 from food. Destruction of these cells results in B12 deficiency. Alcoholism can result in vitamin B12 anemia as can certain medications that inhibit DNA replication such as methotrexate and zidovudine.

Anemia is the most common blood disorder. There are many different types and causes of anemia. Anemia usually results from excessive blood loss, excessive red blood cell destruction or decreased red blood cell production. The symptoms of anemia are vague, so a blood test is the best way to diagnose anemia. Treatment will depend upon the cause of the anemia.

Reference: http://en.wikipedia.org/wiki/Anemia.

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