Pernicious Anemia
A blood disorder characterized by abnormally low numbers
of red blood cells and caused by an inability to absorb
vitamin B12. To absorb vitamin B12, the cells lining
a portion of the stomach make a substance called intrinsic
factor that binds vitamin B12 found in food. Only when
combined with intrinsic factor can vitamin B12 be absorbed
into the blood stream from the intestine. People with
pernicious anemia cannot produce intrinsic factor and
become deficient in vitamin B12, which is needed for
red blood cell production.
Pernicious anemia gets its name from the fact that,
in the days before its cause was understood and effective
treatment developed, it led to gradual, progressive
deterioration and eventual death. Early symptoms include
a sore tongue, a rapid heartbeat, limited endurance,
weakness, abdominal discomfort, and weight loss due
to poor appetite. The disease also affects the nerves;
causing paresthesia (tingling or numbness) in the hands
or feet, difficulty walking, clumsiness, slow though
processes, and impaired memory. Rarely there are psychiatric
symptoms such as hallucinations or paranoia.
Pernicious anemia is usually diagnosed with blood
tests that measure the level of vitamin B12 in the bloodstream.
In some cases a biopsy sample of bone marrow is taken.
Pernicious anemia is a megaloblastic anemia, which is
characterized by the presence of abnormal red blood
cell precursors (megablasts) in the bone marrow.
Once pernicious anemia is diagnosed, it is treated
with regular injections of vitamin B12. Treatment usually
reduces symptoms in 49 to 72 hours. People with pernicious
anemia require injection every month or two for the
remainder of their lives. Treatment should begin as
soon as the disease is diagnosed, since delay can result
in permanent damage to the nervous systems. If treatment
is started early, most people with pernicious anemia
live a normal life.
Pernicious anemia usually does not appear before age
30, although there is an uncommon form of the disease
that arises in children by age 3. Pernicious anemia
is thought to be caused by an unidentified inherited
characteristic and is most common in people of northern
European descent, particularly those with fair hair.
Pernicious anemia also is associated with autoimmune
diseases involving the hormone-producing gland, such
as type-1 diabetes mellitus, Addison disease, and Graves
disease.
Source: AMA Complete Medical Encyclopedia,
Copyright 2003, American Medical Association
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