BODY IRON EXCHANGE IN MAN*

Abstract
Red cell Fe turnover was determined in man by measuring the radioactivity of the circulating blood over a 4-year period after the intravenous injection of Fe55, During the 1st year there was an excessive fall in circulating activity which was attributed to mixing of the isotope with non-erythrocyte Fe. Thereafter, a single exponential slope was observed which was assumed to represent body Fe loss. Fe turnover total miscible body Fe was calculated to be 0.61 mg/day in men, 0.64 mg/day in non-menstruating women and 1.22 mg/day in menstruating women.