Anemia occurs when the number of healthy red blood cells (RBCs) in the body is too low. Red cells carry oxygen to all the body’s tissues, so a low red blood cell count indicates that the amount of oxygen in the blood is lower than it should be. Many of the symptoms of anemia are caused by decreased oxygen delivery to tissues and organs.
Anemia is measured according to the amount of hemoglobin, the protein that carries oxygen, in RBCs. The World Health Organization (WHO) defines anemia as less than 13 grams of hemoglobin per deciliter for men, and less than 12 grams of hemoglobin per deciliter for women. Approximately three million Americans suffer from anemia. Women and people with chronic diseases are at highest risk of anemia.