Low-dose thiazide diuretics in children with idiopathic renal hypercalciuria

Aim: To evaluate the therapeutic effect of hydrochlorothiazide in idiopathic renal hypercalciuria. Methods: We retrospectively analysed the data of 28 children (6.0 +/- 4.1 years, M:F = 19: 9) diagnosed as having idiopathic renal hypercalciuria from the years 1991 to 2008. The dose of hydrochlorothiazide was initially 0.5 mg/kg/day and gradually increased to achieve the appropriate hypocalciuric effect (urinary calcium/creatinine < 0.2 mg/mg) in some unresponsive patients. Results: Twenty-two patients (79%) had gross haematuria, 6 (21%) microscopic haematuria, 2 left flank pain, 6 (21%) urolithiasis and 9 (32%) urinary tract infection at the diagnosis of hypercalciuria. The low doses (0.5 mg/kg/day) of hydrochlorothiazide reduced urinary calcium excretion in 25 patients (89%) and 3 (11%) required the increased doses (1-2 mg/kg/day). Haematuria and urolithiasis gradually resolved in accordance with the improvement of hypercalciuria. Nineteen patients (68%) maintaining hypocalciuria during hydrochlorothiazide therapy were discontinued after 12.5 +/- 5.3 months of treatment. Eleven of the 19 patients maintained normocalciuria, while 8 showed increased urinary calcium excretion at 2.9 +/- 2.3 months after treatment was stopped, requiring thiazide retreatment. Conclusion: Our results suggest that low dose (0.5 mg/kg/day) of hydrochlorothiazide may be safe and effective in controlling renal hypercalciuria in children.