Vitamin B12 is required for a number of metabolic processes. Which of the following lesions would NOT lead to a deficiency of this vitamin?
Chronic gastritis resulting in achlorhydria
Autoimmune destruction of gastric parietal cells
Surgical resection of the jejunum
Surgical resection of the ileum
Absorption of vitamin B12 requires formation of a complex with intrinsic factor, which is secreted by parietal cells of the stomach. Destruction of these cells thus results in a vitamin B12 deficiency. The vitamin B12-intrinsic factor complex is absorbed in the ileum. Thus, surgical resection of the ileum, but not of the jejunum, will also produce a deficiency. Ref: Kaushansky K., Kipps T.J. (2011). Chapter 37. Hematopoietic Agents: Growth Factors, Minerals, and Vitamins. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.