Figure -IgG antiāred cell autoantibodies. A,
Structure of an IgG molecule demonstrating its variable
and constant regions and the heavy and light chains. B,
Agglutination of red cells by pentameric IgM antibodies,
which can join the cells into a lattice. C, Coating of
red cells by IgG antibodies. The antibodies are unable
to agglutinate the cells. D, Agglutination of IgG-coated
red cells by an anti-IgG antibody.
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. SymptomsSome
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.
DiagnosisOnce 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.
TreatmentIn 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. |