Primary hyperparathyroidism. A cause of hypercalciuria and renal stones in patients with medullary sponge kidney.

Three patients with nephrolithiasis were found to have both medullary sponge kidney (MSK) and primary hyperparathyroidism. In all cases, urine calcium excretion returned to normal after parathyroidectomy. The passage of stones was abolished for more than 20 years in one case and for more than 12 years in another. The available data suggest that many patients with MSK are asymptomatic and that the risk of stone formation is increased by an associated metabolic abnormality such as hypercalciuria or hyperparathyroidism.