Susan McDonald, age 14, of Dover, Del., for her question:
WHAT CAUSES ANEMIA?
Anemia is not a disease. It is a symptom or indication of a disease and it occurs when the number of red blood cells or the amount of hemoglobin, or red pigment, in the red blood cells falls below a normal level.
Anemia may be caused by one of three things: a lack of the materials needed for the normal production of red blood cells and hemoglobin, decreased red cell production or increased loss of red cells through destruction or bleeding.
Deficiency anemia may be caused by lack of the necessary diet materials. Or the body may be unable to absorb and use these materials, even though they are present in the diet.
A common type of anemia is called pernicious anemia. It usually results when there is not enough vitamin B 12 in the body. This may occur when the stomach fails to produce a substance called "intrinsic factor," or when the intestines fail either to absorb vitamin B 12 or intrinsic factor.
In pernicious anemia, the red blood cells are not formed properly. Regular hypodermic injections of vitamin B 12 by a doctor may help to keep the blood normal.
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.
Sickle cell anemia and thalassemia are inherited disorders of the red cell. These conditions affect the hemoglobin portion of the cells and defective cells are produced. These defective cells are easily destroyed.
The bone marrow, or center part of the bones, produces the red cells and the red cells produce hemoglobin. To make the red cells, 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 blood cells each day as those that die: about 8 percent of the body's total supply.
Chronic iron deficiency anemia may result from the loss of blood. But it may also be caused by lack of iron in the diet or poor digestion of iron.
In chronic iron deficiency anemia, the skin may become flabby and wrinked, the tongue smooth and shiny and the hair may turn gray. A doctor may correct this condition by the addition of the proper form of iron to the body.
Aplastic anemia results when the bone marrow loses its ability to form blood. It may be caused by exposure to chemicals, such as benzol and xylol, or to certain antibiotic drugs. Large doses of X rays or atomic radiation may also destroy blood forming cells.
Memolythic anemia is a shortening of the life span of red blood cells. This form of anemia may be inherited or acquired. Acquired hemolythic anemia may be caused by an autoantibody or a factor in the blood that attracts its own blood cells.
In rare cases, transfusions may be followed by a severe reaction, which is usually due to mismatching blood.