Investigation and treatment of renal calculi

We have investigated and treated 176 patients who were suffering from renal calculi. The stones contained calcium in 87% of patients, predominantly urate in 11%, and rarely contained magnesium ammonium phosphate or cystine. Of the patients with calcium stones, hypercalciuria was present in 75% and was identified in 57% by the measurement of the 24-hour urinary calcium excretion, and in a further 18% by a standardization calcium 'fast-and-load' test. Nine patients were found to have primary hyperparathyroidism and were treated surgically. A further 21% were suspected to have normocalcaemic hyperparathyroidism, and metabolic studies are being developed to clarify this. The treatment of hypercalciuria included a low-calcium diet, and various combinations of a thiazide diuretic, phosphate supplements and sodium cellulose phosphate. Hypercalciuria was controlled in all compliant patients, and only two developed further stones. Hyperuricosuria was rarely the sole metabolic abnormality in patients with calcium stones, though this might reflect the referral pattern of the Unit. Uric acid stones were frequently, but not invariably, associated with hyperuricosuria and acid urine, and even large uric acid calculi dissolved with a combined therapy of high fluid intake, allopurinol and an alkalinizing agent. Surgical treatment was rarely required in these patients. A stone in the renal pelvis of one patient was removed percutaneously and did not require ultrasonic fragmentation. Modern methods of investigation and treatment have greatly improved the outlook for patients with recurrent renal calculi.