Anemia
Anemia (Greek for “bloodlessness”), a blood condition involving an abnormal reduction in the number of red blood cells (erythrocytes) or in their hemoglobin content. These cells are the means by which oxygen is carried to the various parts of the body. People who are anemic develop symptoms caused by the inadequate delivery of oxygen to their body tissues. There are three primary causes of anemia: (1) reduced production of red blood cells, which may result from deficiency in nutrients or hormones, or from disease or other conditions; (2) excessive destruction of red blood cells, often a hereditary problem; and (3) excessive blood loss. The most common type of anemia is iron-deficiency anemia, which occurs when the body's need for iron increases, as during certain periods of childhood and in pregnancy, or when there is insufficient iron in the diet. Pernicious anemia, a chronic ailment that mostly affects people over 40, is a result of vitamin B 12 deficiency, often caused by decre