Effect of High Calcium Intake on Strontium Metabolism in Man.

Studies carried out with tracer doses of radiostrontium (Sr85) in man have revealed qualitative similarities but quantitative differences in metabolism of strontium and calcium (1-5). The principle of qualitative correlation between urinary excretion of calcium and of radiostrontium has been utilized in investigations of the removal of radiostrontium from man (6). It has been shown that elimination of radiostrontium could be considerably enhanced by inducing an increase of urinary calcium excretion, either by intravenous administration of calcium or by use of the combination of both agents (6). A study was then initiated to investigate the effect of orally administered calcium and of the duration of calcium supplementation on radiostrontium metabolism in man. It was hoped that prolonged oral administration of calcium would lead to a decrease in radiostrontium body burden by decreasing absorption of radiostrontium from the intestinal tract and by increasing its excretion via the kidney due to the concomitant increase of urinary calcium excretion during the phase of high calcium intake. Some of the data on the effect of high calcium intake on Sr85 metabolism in man has been preliminarily presented (7), and the results obtained in these and in additional studies are reported in this communication.