[Renal lithiasis in idiopathic hypercalciuria and primary hyperparathyroidism].

The high incidence of renal lithiasis in hyperparathyroidism (55 p. 100) suggests that PTH plays a causal role in stone production. It also motivates a systematic search for primary hyperparathyroidism in all patients with renal stones although it is only found in about 7 p. 100 of cases. PTH acts through the stimulation of 1.25(OH)2 vitamin D production and therefore, the absorption of calcium from the intestine, which in turn increases the filtrable calcium, hence the calciuria. In renal stones, in general, hypercalciuria represents one of the major metabolic disturbances, besides the hyperoxaluria, hyperuricosuria and the reduction of the inhibitors of crystallization. However, hypercalciuria is rarely the indirect result of excess PTH. It is usually caused by increased dietary ingestion of NaCl, meat, calcium and possibly carbohydrates.