Effect of hydrochlorothiazide on renal hypercalciuria.

The long-term effect of hydrochlorothiazide (HCT) was studied in 30 children (17 boys and 13 girls), aged 4-13 years (mean 7.6 +/- 3.4), with renal hypercalciuria (HCU) for a period of 2.5 +/- 0.95 years. The purpose of the study was to evaluate the effect of HCT mainly on renal calcium excretion, but also on serum K+, Ca, P, Mg, cPTH, nephrogenic cAMP (ncAMP) and bone mineral content (BMC). In addition to the above-mentioned parameters, oxalate, uric acid, citrate and cystine levels in 24-hour urine collections were also measured, and UCa/UCr, UP/UCr, UMg/UCr in 3-hour urine collections were assayed. The results of the study showed that 1 mg/kg/day of HCT caused a rapid and long-lasting correction of HCU, a decrease in serum cPTH and ncAMP, a significant increase in BMC and prevention of the formation of new urinary stones or of the increase in size of stones already present. No side effects were observed.