Condition in which erythrocytes are reduced in number or volume or are deficient in hemoglobin. The patient is usually noticeably pale. Close to 100 varieties exist (including aplastic anemia, pernicious anemia, and sickle-cell anemia), distinguished by cause; erythrocyte size, shape, and hemoglobin content; and symptoms. Anemia may result from blood loss; increased destruction, reduced production, or inhibited formation of red cells; or hormone deficiency. Treatment may involve nutrition, toxin removal, drugs, surgery, or transfusion. See also folic-acid-deficiency anemia, iron-deficiency anemia.

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