Anemia is a deficiency of red blood cells which contain hemoglobin, a chemical that includes iron, gives blood its red color, and carries oxygen from the lungs to the body tissues. It is detected by measuring one or more of three tests done on an automated machine; the red cell count, the hemoglobin concentration, and the hematocrit (a measure of the percentage of the blood occupied by red cells as opposed to plasma).
Anemia results in decreased delivery of oxygen to the tissue unless the heart can compensate by circulating the red cell more frequently. If less oxygen is delivered symptoms develop- mainly fatigue and shortness of breath. Severe anemia can cause pallor, rapid and forceful heartbeats and pounding headache. For no known reason, severe iron deficiency anemia may cause a craving for ice (Pagophagia).
The many causes of anemia can be divided into those in which red cell survival is shortened due to either hemorrhage or to increased destruction in the circulation (hemolytic anemia), and those in which red cell production is decreased. Hemorrhage is most commonly from trauma such as an auto accident or from the gastrointestinal tract as with bleeding gastric ulcers. In the latter case bloody vomitus or bloody stools are seen. Hemolytic anemia is evaluated by a reticulocyte count, which measures the rate of production of red cells. This is elevated above the normal of 1%. It is most commonly hereditary, sickle cell anemia being the commonest. Acquired hemolytic anemia is usually caused by an antibody against red cells (autoimmune hemolytic anemia). This disease and the antibody causing it are detected by a Coombs test.
Of the anemias caused by decreased production, iron deficiency is the most common. This in turn is almost always due to slow bleedings either menstrual or from the gastrointestinal tract such as from stomach ulcers or colon cancers. Although rare in developed countries, worldwide hookworm infection is the most common cause. Also pregnant women become deficient by giving iron to their fetuses. The best test for iron deficiency is a serum ferritin, which measures total body iron stores. If this is low and the patient is not a menstruating or a pregnant woman, an evaluation of the gastrointestinal tract usually with gastroscopy and colonoscopy is required.
Deficiency of Vitamins B-12 or folic acid is a rare cause of anemia and is evaluated by measurement of these vitamins in the serum. Disorders of the bone marrow (the site of red cell production) are uncommon. These are often diagnosed by bone marrow analysis.
The treatment of anemia depends on the diagnosis. Iron is only helpful for iron deficiency and for vitamin B-12 deficiency. Anemias of chronic diseases are treated by treatment of the chronic disease. Anemia from kidney failure can be treated by injections of Erythropoietin, a substance produced by the kidneys, which stimulates the bone marrow to produce red cells. This is less helpful for other causes of anemia. Anemia of bone marrow diseases such as leukemia resolve when the disease is treated effectively. Occasionally no treatment is possible and red cell transfusions are necessary on a regular basis.
Liver and injections of liver extract have been used in the past. These helped because they contain iron and vitamin B-12 that is now given in purified form orally or by injection.
In summary, anemia is not caused by one thing and is not treated by one medication. To be treated effectively, a diagnosis must be made by appropriate testing.
Authored by: George Conklin, M.D
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