The Behavior of Strontium-85 in a Normal Man Following a Single Ingestion—Absorption and Excretion

Abstract

The rate of fecal and urinary excretion of strontium-85 following a single ingestion, in a normal adult, was measured up to 162 days. Large amounts of unabsorbed strontium were found in the feces during the first 3 days, and only 13.6 per cent of the dose was absorbed. The absorbed portion of the radioactivity showed the turnover of a three-stage process, (1) rapid excretion, (2) an intermediate-rate process, and (3) a chronic retention stage, in accordance with the dose injected intravenously. The urinary-total excretion ratio was ⅔ except for the first 3 days. The variation of plasma concentration of strontium-85 was measured over the first 44 hr after ingestion, and calcium intake and excretion were also measured. It is shown that the urinary excretion of strontium-85 is closely linked with that of calcium and the plasma concentration of strontium-85.