Which disorders of the ileum may lead to pernicious anemia?

Updated: Feb 18, 2019
  • Author: Srikanth Nagalla, MD, MS, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Disorders of the ileum cause cobalamin deficiency as a consequence of the loss of the ileal receptors for the cobalamin-IF complex. Thus, surgical loss of the ileum and diseases such as tropical sprue, regional enteritis, ulcerative colitis, and ileal lymphoma interfere with cobalamin absorption.

Genetic defects of the ileal receptors for IF (ie, Imerslünd-Grasbeck syndrome) and hereditary transcobalamin I (TCI) deficiency produce cobalamin deficiency from birth and are usually discovered early in life.

Many drugs impair cobalamin uptake in the ileum but are rarely a cause of symptomatic vitamin B12 deficiency, because they are not taken for long enough to deplete body stores of cobalamin. Such agents include nitrous oxide, cholestyramine, para -aminosalicylic acid, neomycin, metformin, phenformin, and colchicine.


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