[Thiazides to prevent recurrence of kidney stones: is hydrochlorothiazide still indicated?]

Thiazides are widely used to prevent recurrence of calcium-containing kidney stones. However, the recent NOSTONE trial reported no benefit of hydrochlorothiazide on the composite outcome of symptomatic or radiologic recurrence. Higher doses (25 and 50mg daily) resulted in a decrease of radiologic recurrence, but no difference in symptomatic stones. Current guidelines preserve the use of hydrochlorothiazide to patients with overt hypercalciuria, while NOSTONE also included patients without hypercalciuria. This might have underestimated the effect of hydrochlorothiazide. While patients received dietary counseling, results suggest adherence was poor e.g. with respect to oxalate and salt consumption, possibly mitigating a potential beneficial hypocalciuric effect of hydrochlorothiazide. Furthermore, previous studies that did show an effect of thiazides on stone recurrence used higher doses. Thus, while hydrochlorothiazide might not be effective in all patients with calcium-containing kidney stones, it should not be written off, as its efficacy in overt hypercalciuria needs to be further elucidated.