[Idiopathic hypercalciuria. Correlative study of bone tissue and phosphocalcium investigations]

The authors report on the clinical, biological and radiological anomalies observed in a series of 42 cases of idiopathic hypercalciuria. An histological bone study showed "osteomalacia" type changes (an increase in the osteoid volume and a decrease in the mineralization speed). The Ca45 isotope studies showed that there was an exchangable pool of calcium and a turnover, which was generally low. A study of the kidney functions revealed a decrease in the tubular reabsorption of calcium, while that of phosphorous remained within normal limits. There was no case of hyperparathyroidism in this series. The authors pose the question of whether the failure of calcium to settle on the tissues and the lack of tubular reabsorption of calcium, does not result from the relatively ineffective action of the endogenous circulating parathyroid hormone.