Autoimmune hemolytic anemia is a group of disorders characterized by a malfunction of the immune system that produces autoantibodies, which attack red blood cells as if they were substances foreign to the body.
Autoimmune hemolytic anemia is an uncommon group of disorders that can occur at any age. These disorders affect women more often than men. About half of the time, the cause of autoimmune hemolytic anemia cannot be determined (idiopathic autoimmune hemolytic anemia). Autoimmune hemolytic anemia can also be caused by or occur with another disorder, such as systemic lupus erythematosus (lupus), and rarely it follows the use of certain drugs, such as penicillin.
Destruction of red blood cells by autoantibodies may occur suddenly, or it may develop gradually. In some people, the destruction may stop after a period of time. In other people, red blood cell destruction persists and becomes chronic. There are two main types of autoimmune hemolytic anemia: warm antibody hemolytic anemia and cold antibody hemolytic anemia. In the warm antibody type, the autoantibodies attach to and destroy red blood cells at temperatures equal to or in excess of normal body temperature. In the cold antibody type, the autoantibodies become most active and attack red blood cells only at temperatures well below normal body temperature.
Some people with autoimmune hemolytic anemia may have no symptoms, especially when the destruction of red blood cells is mild and develops gradually. Others have symptoms similar to those that occur with other types of anemia, especially when the destruction is more severe or rapid. When severe or rapid destruction of red blood cells occurs, mild jaundice may also develop. When destruction persists for a few months or longer, the spleen may enlarge, resulting in a sense of abdominal fullness and, occasionally, discomfort.
When the cause of autoimmune hemolytic anemia is another disease, symptoms of the underlying disorder, such as swollen and tender lymph nodes and fever, may dominate.
Once doctors diagnose anemia, increased destruction of red blood cells is suspected when a blood test shows an increase in the number of red blood cells that are immature (reticulocytes). Alternatively, a blood test may show an increased amount of a substance called bilirubin and a decreased amount of a protein called haptoglobin.
Autoimmune hemolytic anemia as the cause is confirmed when blood tests detect increased amounts of certain antibodies, either attached to red blood cells (direct antiglobulin or direct Coombs' test) or in the liquid portion of the blood (indirect antiglobulin or indirect Coombs' test). Other tests sometimes help determine the cause of the autoimmune reaction that is destroying red blood cells.
If symptoms are mild or if destruction of red blood cells seems to be slowing on its own, no treatment is needed. If red blood cell destruction is increasing, a corticosteroid such as prednisone is usually the first choice for treatment. High doses are used at first, followed by a gradual reduction of the dose over many weeks or months. When people do not respond to corticosteroids or when the corticosteroid causes intolerable side effects, surgery to remove the spleen (splenectomy) is often the next treatment. The spleen is removed because it is one of the places where antibody-coated red blood cells are destroyed. When destruction of red blood cells persists after removal of the spleen or when surgery cannot be done, immunosuppressive drugs, such as cyclophosphamide or azathioprine, are used.
When red blood cell destruction is severe, blood transfusions are sometimes needed, but they do not treat the cause of the anemia and provide only temporary relief.
Last full review/revision June 2008 by Alan E. Lichtin, MD