Vitamin B12 deficiency

(NEJM 2013;368:149)

• B12 present only in foods of animal origin; total body stores sufficient for 2–3 y

• Binds to intrinsic factor (IF) secreted by gastric parietal cells; absorbed in terminal ileum

• Etiologies of Vitamin B12 deficiency:

• clinical manifestations of vitamin B12 deficiency:

• Dx: ↓ B12 (even low nl); ↑ homocysteine & methylmalonic acid; anti-IF Ab; ↑ gastrin in PA

• Treatment-Vitamin B12 deficiency:

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