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Ency. home > Disease > P > Pernicious anemia

Pernicious anemia   

Overview | Symptoms | Treatment | Prevention

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 vitamin B12 (cobalamin) from the gastrointestinal tract.

Causes and Risks

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.

Other causes of pernicious anemia include atrophic gastric mucosa, autoimmunity against gastric parietal cells, and autoimmunity against instrinsic factor.

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.

In addition to pernicious anemia, other causes of Vitamin B12 Deficiency include:

  • nutrition (strict vegetarians without B12 supplementation, 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)

Ency. home > Disease > P > Pernicious anemia

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