Evidence for the Fundic Origin of Intrinsic Factor

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Abstract
These studies indicate that most intrinsic factor activity is present in the fundus, with little or none in the antrum. No in vivo confirmatory studies have as yet been reported. A patient with the Zoolinger-Ellison syndrome for which a parietal cell mass resection (fundectomy) leaving only the antrum was performed afforded an opportunity to delineate in vivo the site of origin of human intrinsic factor. The operative procedure consisted of fundectomy with ileocolonic transplant and preservation of the antrum. The demarcation between fundus and antrum was accomplished with Congo red. Vitamin B12 absorption, measured by the Schilling test, was normal prior to the operation whereas postoperatively no absorption of Vitamin B12 was effected unless Hog intrinsic factor was given. The patient''s post-surgical gastric juice was utilized in an attempt to correct the Vitamin B12 absorptive defect in a patient with known pernicious anemia. No augmentation of Vitamin B12 absorption was produced whereas, normal gastric juice as well as Hog intrinsic factor corrected the Schilling test of the pernicious anemia subject to normal. Gastric juice electrophoresis was also performed on the patient''s post-surgical gastric juice and revealed a pattern similar to pernicious anemia. This study adds clinical support to previous laboratory studies citing the fundus and not the antrum as the site of production of intrinsic factor.