Abstract

The intestinal absorption of ⁵⁷Co vitamin B₁₂ has been measured by counting the radioactivity in the serum, and the effect of the parenteral administration of 1 mg. non-radioactive vitamin B₁₂ two hours after the oral dose has been studied. When parenteral vitamin B₁₂ was not given, the mean radioactivity in the serum was lower in both patients with pernicious anaemia and in control subjects, and the results in the patients with pernicious anaemia were more definitive. There was no significant difference between the results obtained with an Ekco scaler and those with an I.D.L. scaler.

This is the simplest and most convenient method of measuring vitamin B₁₂ absorption. It is suggested that the test be standardized by giving 0·5 μg. ⁵⁷Co vitamin B₁₂ with a maximal histamine stimulation of intrinsic factor secretion, but without a parenteral dose of non-radioactive vitamin B₁₂. The results are expressed most usefully as a percentage of the administered dose per litre of serum or plasma.