 Intrarenal calcifications nephrocalcinosis is present in Dents disease and likely contribute to progression toward renal failure. In order to prevent this complication it is usually proposed to treat affected patients during childhood with high doses of thiazides. Indeed, this class of diuretics is used for years to treat hypertension, can lower urinary calcium excretion. However the doses usually used are high, are known to be associated with adverse events such as severe potassium depletion, decrease in blood pressure and dehydration. The purpose of the study was to test whether lower dose of thiazides would be better tolerated, with similar efficacy to lower urinary calcium excretion, as previously demonstrated in other indication such as treatment of hypertension. 