Investigation and treatment of renal calculi associated with hypercalciuria.

Thirty-four patients presenting to a urology clinic over a five-year period with renal calculi and either hypercalciuria or hypercalcemia were investigated by measurements of serum parathyroid hormone and urinary calcium and cAMP. Ten patients were hypercalcemic and were found to have primary hyperparathyroidism. Of the remaining patients all but one had excessive urine calcium excretion after an oral calcium load. In addition, 9 patients were shown to have elevated fasting urinary calcium levels while on a low-calcium diet, raising the possibility of impaired renal calcium conservation as one factor causing their hypercalciuria. The measurement of urinary cAMP levels did not contribute to the accuracy of diagnosis and did not permit further subclassification into different types of hypercalciuria. There was a decrease in urinary calcium excretion and a marked reduction in stone-related events in 10 patients with severe renal stone disease during treatment with hypocalciuric agents.