Kimberly Miller, age 14, of DeKalb, I11., for her question:
WHAT CAUSES ANEMIA?
Anemia occurs when the number of red blood cells or the amount of hemoglobin in them falls below normal. Hemoglobin is the blood's red pigment.
Anemia may be caused by one of three important things: a lack of the materials needed for normal red cells and hemoglobin production, decreased red cell production or increased loss of red cells through either destruction or bleeding.
Anemia is not in itself a disease but rather it is a symptom of one.
The center part of the bones, called the bone marrow, produces the red cells and the red cells produce hemoglobin. To make them, the marrow needs iron, vitamin B 12 and other B vitamins, vitamin C and certain proteins.
Normally, the bone marrow produces about as many red cells each day as those that die about 0.8 percent of the body's total supply.
Deficiency anemia may be caused by a lack of the necessary diet or food materials. Or the body may be unable to absorb and use those materials, even though they are present in the diet.
Chronic iron deficiency anemia often results from the loss of blood. But it may be caused by lack of iron in the diet, poor digestion of iron, or severe diarrhea. In this type of anemia, the skin may become flabby and wrinkled, the tongue smooth and shiny and the hair may turn gray. A doctor may correct this condition by adding the proper form of iron to the body.
Pernicious anemia usually results when there is not enough vitamin B 12. This may occur when the stomach fails to produce a substance called "intrinsic factor," or when the intestines fail to either absorb vitamin B 12 or intrinsic factor. As a result, the red blood cells are not formed properly. Regular hypodermic injections of vitamin B 12 keep the body normal.
Bone marrow anemia occurs when the bone marrow stops growing or when abnormal cells invade the bone marrow. The number of white cells and platelets, or small parts of cellular material, are also reduced.
Aplastic anemia results when the bone marrow loses its ability to form blood. It may be caused by exposure to some chemicals, X rays or radiation.
Sickle cell anemia and thalassemia are inherited disorders of the red cells. These conditions are concerned with defective hemoglobin or faulty hemoglobin production.
Other hereditary hemolytic disorders are caused by faults in red cell enzymes or in the structure of red cells.
Blood loss anemia is caused by hemorrhage or excessive bleeding. The site of bleeding is usually easy for doctors to locate. But in some cases, the site may be hidden and small amounts of blood may leak from the bowel.
Hemolytic anemia is a shortening of the life span of red blood cells. This form of anemia may be inherited or acquired. Acquired hemolytic anemia may be caused by an autoantibody which is a factor in the blood that attacks its own blood cells. In rare cases, transfusions may be followed by a severe reaction, which is usually due to mismatching blood.