Autoimmune Hemolytic Anemia
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 disease, such as systemic lupus erythematosus,
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; whereas in other
people, it 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.
Symptoms
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 disease, such as swollen
and tender lymph nodes and fever, may dominate.
Diagnosis
Once a doctor diagnoses 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 Coombs test) or in the liquid portion of the blood (indirect
antiglobulin or Coombs test). Other tests sometimes help determine
the cause of the autoimmune reaction that is destroying red blood
cells.
Treatment
In many cases celiac disease is causing
the auoimmune anemia, so please read the
celiac anemia section.
If symptoms are mild or if destruction of red blood
cells seems to be slowing on its own, no treatment is needed.
If a drug has caused the problem, the offending drug
needs to be stopped.
If red blood cell destruction is worsening, a
corticosteroid drug such as prednisone is usually the first choice
for treatment. High doses are used at first, followed by a gradual
tapering of the dose over many weeks or months.
I.V.I.g may be used when steroids are ineffective.
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. When
destruction of red blood cells persists after removal of the spleen
or when surgery cannot be performed, immunosuppressive drugs, such
as cyclophosphamide or azathioprine, are used.
Plasmapheresis, which involves filtering blood to
remove antibodies, is occasionally helpful when other treatments
fail. 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.
|
