A Dual Mechanism of Vitamin B12 Plasma Absorption1

Open Access
Publisher Website
Google Scholar
Abstract
Comparison between the plasma absorption curves in control subjects and patients with pernicious anemia after the administration of radio-labeled vitamin B12 suggests a dual mode of absorption depending upon the size of the test dose. A delayed peak of plasma radioactivity found with test doses of 0.56 [mu]g was dependent upon intrinsic factor and was lacking in patients with pernicious anemia. An earlier rise in plasma radioactivity was found with test doses of 50-500 [mu]g. This earlier rise was independent of intrinsic factor and was present in normal subjects as well as in patients with pernicious anemia.