BOUND VITAMIN-B12 ABSORPTION IN PATIENTS WITH LOW SERUM-B12 LEVELS

In many patients with low serum levels of vitamin B-12, the absorption of the free vitamin has been normal. The present study, using a total body counter (CoB)-Co-57-B-12 absorption method that clearly separated those with intrinsic factor deficiency from controls, found that of 94 patients with low B-12 levels and intact stomachs in whom the absorption of free and bound B-12 was determined, 44(47%) had normal absorption of both. However, 20 of the 94 (21%) with normal absorption of free B-12 had low absorption of bound B-12. The remainder (32%) had low absorption of both free and bound B-12. All patients with high serum gastrin levels had low bound B-12 absorption, but so did 21% of those patients with normal serum gastrin levels.