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Anemia, Hemolytic

What is it?

Hemolytic anemia occurs when circulating red blood cells are destroyed prematurely. Often the bone marrow cannot produce new red cells fast enough to compensate for the increased destruction (despite the fact that marrow is capable of producing red cells at up to six times the normal rate). The disorder is rarely life-threatening, but it may be difficult to treat.

What Causes It?

  • Hemolytic anemia is either inherited or acquired. Inherited cases are due to a genetic abnormality in the red cells themselves, and anemia generally appears early in life. Hereditary forms include hemoglobinopathies such as sickle cell anemia, red cell membrane disorders like hereditary spherocytosis (a condition in which the red cells are spherical instead of the normal doughnut shape), and red cell enzyme disorders such as glucose-6-phosphate dehydrogenase (G6PD) deficiency.
  • In people with G6PD deficiency, red cell destruction (hemolysis) is usually provoked by exposure to certain substances. These include certain types of drugs such as sulfonamides and antimalarials, the medication nitrofurantoin, and the active ingredient in mothballs.
  • Hemolytic anemia in one form of G6PD deficiency, common in the Greek isles, results from the ingestion of fava beans (or inhalation of pollen from the plant).
  • Infection, fever, or disturbances of normal metabolism can also initiate hemolysis.
  • Certain viral, bacterial, or parasitic infections can cause red cell destruction.
  • For unknown reasons, the body occasionally produces antibodies to its own red cells. This is known as autoimmune hemolytic anemia and may occur alone or as a consequence of other diseases, such as lymphoma or lupus.
  • Transfusion with incompatible blood will result in either immediate and severe or delayed hemolysis.
  • Abnormalities in the lining of the blood vessels, artificial heart valves, or blood clots may cause mechanical damage that destroys red cells.
  • Certain drugs, such as antibiotics, antihypertensives, and antiarrhythmics can cause hemolysis by either immune or nonimmune mechanisms.

Prevention

  • When hemolytic anemia is provoked by specific substances, avoiding those substances can prevent recurrence.

Diagnosis

  • Blood tests, including a complete blood count, are necessary.
  • A family history is conducted.
  • Occasionally, when hemolysis is very mild and there is little evidence of anemia, a radioactive chromium test may be performed to assess red cell survival, which is always shortened.
  • Other more specialized tests for abnormalities of the red cell membrane, enzymes, or hemoglobin may be necessary.
  • Occasionally, a bone marrow sample may be taken to look for underlying disorders that could cause hemolytic anemia.
  • Chronic hemolytic anemia can cause gallstones; therefore, a gallbladder x-ray may be necessary.

How to Treat It

  • Immunosuppressant drugs, such as corticosteroids (prednisone, for example), may be useful in cases caused by an autoimmune disorder.
  • Anemia due to hereditary spherocytosis or autoimmune hemolysis can be greatly improved by removal of the spleen (splenectomy), as the spleen is the primary site of red cell destruction.
  • Blood transfusions are sometimes required as emergency treatment.
  • Folic acid supplementation should be provided.
  • Some types of hemolytic anemia require supplementation with iron.
  • For individuals with G6PD deficiency, which is common in African-Amer icans or individuals from the Mediterranean basin, avoidance of exposure to certain drugs or chemical substances is important to prevent hemolysis.

When to Call a Doctor

  • Any symptoms of anemia warrant a call to your doctor.