Impaired assimilation of egg Co 57 vitamin B 12 in patients with hypochlorhydria and achlorhydria and after gastric resection.

Abstract

Abstract Patients who have undergone gastric resection and those with simple gastric hypochlorhydria and achlorhydria may have low serum B 12 concentrations with normal absorption of radiocyanocobalamin. Impaired assimilation of food vitamin B 12 , but not of the crystalline Co 57 B 12 , may be the cause for this phenomenon. This hypothesis was tested by comparing the assimilation of Co 57 B 12 incorporated into eggs in vivo with that of crystalline Co 57 B 12 . As judged by the urinary excretion test, 10 patients with gastric resection having low serum B 12 , values and normal absorption of crystalline B 12 , absorbed on the average 9% of that observed in 11 normal control subjects when the egg Co 57 B 12 was administered. Similarly, 5 patients with achlorhydria or severe hypochlorhydria absorbed on the average 12% of that seen in normal subjects. There was no difference in the absorption of the crystalline Co 57 B 12 in these groups. An equally poor assimilation of nonlabeled food B 12 may explain the low serum B 12 concentrations found in postgastrectomy patients, and achlorhydric subjects with low serum B 12 and normal absorption of crystalline radiocyanocobalamin. Patients with pernicious anemia and those with gastric resection showing low serum B 12 concentrations and B 12 absorption values had extremely poor assimilation of both food Co 57 B 12 and crystalline Co 57 B 12 .