Influence of an orally administered calcium-binding cation exchanger on calcium metabolism in the rat.

The kinetics of calcium metabolism in the rat were analysed by doing a calcium balance and an assay with 45Ca after feeding a calciumbinding ion exchanger during 3 weeks. Serum and urine concentrations of inorganic phosphate and of calcium were estimated. The increase in the size of the exchangeable calcium pool, the activation of bone turnover, the hypophosphataemia and hyperphosphaturia, as well as hypercalciuria are evidence for a reactive hyperparathyroidism. The results of these experiments call for further investigations concerning the influence of cation exchangers on bone metabolism under clinical conditions.