title: [Optimal dosage of chlorthalidone in the prevention of the recurrence of nephrolithiasis is 25 mg per day].
abstract: Thiazides are considered to be effective in preventing recurrence of various types of nephrolithiasis, but the optimum dosage has not been established. To address this issue, 5 idiopathic stone formers with hypercalciuria on low Ca diet received chlorthalidone (CT) in 3 different oral doses and were randomly assigned either to the sequence 25-50-100 mg/day or the reverse (2 months per dose, monthly blood and urine measurements). The anticalciuric effect of CT was significant only at 50 and 100 mg/day, at the expense of a dose-dependent decrease in U-citrate excretion. We also observed a dose-dependent decrease in blood levels of K, increases in those of HCO3 and urate, as well as in U-pH, a tendency for blood levels of Mg and U-oxalate excretion to fall, and no change in U-urate excretion. Therefore, to derive the optimal CT dose the Tiselius' risk index was applied, which is based on the values of urinary [Ca], [oxalate], [Mg], [citrate] and volume. CT produced a decrement in risk index which was similar at each of the doses tested. Thus, raising CT doses beyond 25 mg/day does not hold out the prospect of improved prophylaxis. This agrees with Ettinger's preliminary data (Urol. Res., 1984) showing a similar protective effect of CT at 25 and 50 mg/day despite the absence of a significant anticalciuric effect at 25 mg/day.
mesh_terms: D002118:Calcium / Q000652:urine*; D002752:Chlorthalidone / Q000008:administration & dosage / Q000627:therapeutic use*; D003460:Crystallization; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007669:Kidney Calculi / Q000188:drug therapy* / Q000517:prevention & control / Q000652:urine; D008297:Male; D012008:Recurrence
chemical_list: D002752:Chlorthalidone; D002118:Calcium
vernacular_title: La posologie optimale de chlorthalidone pour prévenir la récidive de néphrolithiase est 25 mg/j.