A technic is described to measure directly the intestinal absorption of radiovitamin B12 by using a whole-body gamma spectrometer. A double tracer technic is used, and the amounts of free and intrinsic factor bound vitamin B12, respectively, retained in the body after final excretion of unabsorbed radioactivity, are measured. The results are in agreement with those previously obtained by other methods. The present method is simple and quantitative.
The primary advantage of the whole-body counter for measuring absorption of Cobalt-labeled B12 is that it can measure less than 0.1 µc. with a high degree of accuracy. Whole-body counting substitutes a rapid and simple measurement for the difficult and tedious collection and radiochemical analysis of excreta.