Pernicious anemia
Alternative names:
Addison's anemia; Biermer's anemia; macrocytic achylic anemia;
congenital pernicious anemia; juvenile pernicious anemia;
vitamin B12 deficiency (malabsorption)
Definition:
A form of anemia caused
by a lack of intrinsic factor,
a substance needed to absorb (cobalamin) vitamin
B12 from the gastrointestinal tract.
Causes, incidence, and risk factors:
intrinsic factor is
a binding protein required for the absorption of vitamin
B12. Pernicious anemia results from a lack of intrinsic
factor in gastric secretions which, in turn, causes inadequate
vitamin B12 absorption. Vitamin B12 deficiency is the result.
The vitamin B12 deficiency causes a form of anemia specifically
referred to as megaloblastic anemia.
A lack of intrinsic factor is the most common cause of vitamin
B12 deficiency. Intrinsic factor is produced by cells within
the stomach. In adults, the inability to make intrinsic factor
is the result of chronic gastritis or is the result of gastrectomy.
The onset of the disease is slow and may span decades. Very
rarely, infants and children lack the ability to produce effective
intrinsic factor. This form of congenital pernicious anemia
is inherited as an autosomal recessive disorder. However,
most often, megaloblastic anemia
in children results from other causes of vitamin B12 deficiency
or other vitamin deficiencies.
Although a juvenile form of the disease can occur in children,
pernicious anemia usually does not appear before the age of
30. The average age at diagnosis is 60 years. In fact, one
recent study revealed that nearly 2 percent of individuals
over 60 years old suffer from pernicious anemia. Furthermore,
slightly more women than men are affected. The disease can
affect all racial groups, but the incidence
is higher among people of Scandinavian or Northern European
descent.
Risk factors include a family history of pernicious anemia,
Scandinavian or Northern European descent, and a history of
autoimmune endocrine
disorders. Pernicious anemia is seen in association with some
autoimmune endocrine
diseases such as type 1 diabetes,
hypoparathyroidism, Addison's
disease, hypopituitarism,
testicular dysfunction, Graves
disease, chronic thyroiditis,
myasthenia gravis, secondary amenorrhea, and vitiligo.
(See also megaloblastic anemia)
Causes of Vitamin B12 Deficiency:
- Pernicious anemia
- Nutritional (strict vegetarians, poor diet in infant
or poor maternal nutrition during pregnancy)
- Infection (intestinal parasites, bacterial overgrowth)
- Gastrointestinal disease (surgical resection, celiac
disease (sprue), Crohn's disease)
- Drugs (colchicine, neomycin, tuberculosis treatment with
para amino salicylic acid)
- Metabolic disorders (methylmalonic aciduria, homocystinuria)
Updated Date: 06/22/00
Adam S. Levy, MD Chief Fellow, Department
of Pediatrics Memorial Sloan-Kettering Cancer Center , VeriMed
Health Network
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