Anemia is a general term referring to a shortage of red blood cells or a reduction in their hemoglobin content. (Hemoglobin is the pigment in the blood that carries oxygen in the red blood cells.) A shortage of red blood cells or hemoglobin indicates that the blood is unable to transport adequate amounts of oxygen to all parts of the body.

Causes

Anemia can be caused by vitamin or mineral deficiencies or the inability to absorb certain vitamins, the destruction of red blood cells, blood loss through bleeding, inherited abnormalities in the blood, or the failure of the bone marrow to manufacture enough red blood cells.

Such diverse conditions as bleeding ulcers, drug allergies, cancer, and exposure to radioactivity can also lead to anemia. People with poor diets or histories of alcoholism are likely to suffer from one of the types of anemia caused by vitamin and mineral deficiencies. A tendency toward certain types of anemia (for example, sickle-cell anemia) can also be inherited.

Symptoms

Among the many symptoms of anemia are fatigue, shortness of breath, pounding heartbeat, rapid heart rate, headaches, loss of appetite, dizziness, ringing in the ears, weakness, and faintness. Burning of the tongue or a change in its appearance may also be a clue.

Another sign of anemia may be paleness in the creases of the palms, under the fingernails, and in the lining of the eye. Very severe cases may be signaled by swollen ankles; a rapid and weak pulse; pale, clammy skin; and a feeling of fullness in the neck or abdomen.

Diagnosis

Diagnosis is based on the findings from a physical examination and tests of the blood (and sometimes the bone marrow) to detect shortages of red blood cells or hemoglobin. A specific diagnosis is necessary because each type of anemia has a different cause and so needs a different medical treatment.

Iron-Deficiency Anemia

Iron-deficiency anemia results from a shortage of the mineral iron, which is necessary to produce hemoglobin. This shortage can be caused by a variety of conditions, including a drastic blood loss, such as from an accident; chronic blood loss, such as from a bleeding ulcer; hookworm infestation; and a diet lacking in good sources of iron.

Women are particularly susceptible to iron deficiency anemia because of the regular loss of blood during menstruation and the depletion of iron by the fetus during pregnancy. This type of anemia can be treated with iron supplements (ferrous sulfate or ferrous gluconate tablets).

Folate-Deficiency Anemia

Folate-deficiency anemia is caused by either insufficient dietary folate, which is necessary for hemoglobin production, or insufficient absorption of folate from food. This deficiency may be caused or aggravated by malnourishment or alcoholism.

Some disorders of the small intestine, such as inflammatory bowel disease, may also cause it. It is treated with folate and sometimes additional supplements. Because so many foods are enriched with folate today, this type of anemia is less common than it used to be.

Pernicious Anemia

Pernicious anemia arises if the body is unable to absorb vitamin B12, which is necessary for the production of red blood cells in the bone marrow. Intrinsic factor, a substance that helps to absorb vitamin B12, is lacking in the stomach of a person suffering from pernicious anemia. Inability to absorb vitamin B12 can also be caused by some parasites, inflammatory bowel disease, and diseases of the small intestine. Pernicious anemia is treated with vitamin B12 injections directly into the bloodstream, so that the vitamin is not destroyed by stomach acid.

Aplastic Anemia

Aplastic anemia is a serious condition caused by the inability of the bone marrow to produce white and red blood cells and platelets. Bone marrow function can be inhibited by cancer or exposure to radioactivity, hazardous chemicals, or some drugs. This variety of anemia is treated with blood transfusions and bone marrow transplants.

Hemolytic Anemias

Hemolytic anemias are caused by the destruction of red blood cells. These anemias can be either acquired (developed over time) or congenital (present at birth).

Acquired hemolytic anemias can be caused by mismatched blood transfusions, a drug allergy, cancer, or a serious infection. Treatment of the primary condition is necessary to treat the resulting anemia. Blood transfusions can be used to treat the condition temporarily.

Congenital hemolytic anemias are caused by an inherited abnormality in the red blood cells. The most common type is sickle-cell anemia, a disorder that predominantly affects black people. In this form of anemia, the red blood cells, which are sickle shaped instead of disklike, cannot carry enough oxygen. These cells are also very fragile and hemolyze (break down) easily.

This disease is characterized by crisis periods of severe joint or abdominal pain and can lead to complications, such as kidney disease, gallstones, and heart failure. Sickle-cell anemia is treated with painkillers, oxygen, and transfusions. Avoiding situations in which oxygen may be scarce, such as high altitudes, is advisable.

Prevention

There are no specific methods to prevent anemias other than selecting a balanced diet to prevent those anemias caused by vitamin and mineral deficiencies. Individuals may also obtain genetic counseling if a hereditary condition appears to be a possibility.