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Pernicious Anemia
(Vitamin B-12 Deficiency)

What is Pernicious Anemia (Vitamin B-12 Deficiency)?

  • Pernicious anemia is a type of anemia (reduced number of red blood cells or hemoglobin in the body) due to the body's inability to absorb vitamin B-12 from the gastrointestinal tract.
  • Symptoms from anemia are a result of the decreased capacity of the blood to carry oxygen and include fatigue and shortness of breath. In addition, the deficiency of vitamin B-12 also can damage the nervous system.
  • Vitamin B-12 is also known as cobalamin (Cbl). Animal products, both meat and dairy, are the only dietary sources of vitamin B-12 for humans. Because the body has stores of vitamin B-12, inadequate dietary intake must persist for years before a true deficiency of vitamin B-12 occurs.
  • For this reason, the pernicious anemia usually takes years to establish and is most commonly diagnosed in adults with an average age of 60.
  • Also, a rare, form of pernicious anemia called congenital pernicious anemia is present at birth.
  • Pernicious anemia is a form of megaloblastic anemia. Megaloblastic anemia is characterized by an abnormally large size of red blood cell (megaloblast) that is formed by the bone marrow when vitamin B-12 or folic acid levels are low.
  • Megaloblastic anemia can also develop with other conditions that affect the bone marrow and as an effect of some chemotherapy drugs.
  • Bacterial overgrowth in the gastrointestinal tract can also cause a lack of B-12.
Medically Reviewed by a Doctor on 12/16/2015

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