Selenium metabolism in healthy adults: quantitative aspects using the stable isotope 74SeO3(2-)

Using the novel method of stable isotopes, kinetics of appearance and disappearance of 74Se in feces, blood, and urine from four young adult males given single and multiple oral doses of 74SeO32- are described. It is shown that this method is suitable as an alternative to the use or radioselenium and permits detailed evaluation of both kinetics and quantitative aspects of absorption, excretion, and retention of selenium in human subjects. The data provided in this manuscript generally confirm the current understanding of the role of gastrointestinal tract and the kidneys in regard to the regulation of selenium nutriture of human subjects. From the peak appearance of the ingested label in urine it is apparent that there is an early preferential urinary excretion of he ingested label in comparison with the native plasma selenium. The present methodology is readily applicable in detailed studies of urinary forms of the excreted label and elucidation of the time course of metabolism of the ingested label as regards its conversion to the urinary metabolites.