A quantitative method for measuring the gastrointestinal absorption of iron. Blood 15:36

T HE AVAILABILITY of radioisotopes of iron has made it possible to quantitate the metabolic cycle of iron with respect to the erythrocyte. With previous technics using radioiron, however, the fraction of an oral dose of iron absorbed by normal persons is relatively small-2 to 27 per cent-which limits the interpretation of results in studying the gastrointestinal absorption of iron. Particularly, these technics are inadequate for use in syndromes of decreased iron absorption. It seems that the ideal test for absorption of iron would have normal values approaching 50 per cent of the oral dose, so that both increased and decreased absorption could be quantitated. The currently proposed test was designed to achieve this. Two factors helped to increase normal absorption to the 50 per cent level: limiting the dose of iron to 50,tg., and accentuating absorption by the addition of ascorbic acid. Because of the sensitivity of the scintillation detector employed, a 1 ftc. dose of Fe59 was found to be an adequate tag. The method, as outlined herein, is simple, relatively short, and convenientl