The effects of thiazides on serum and urinary zinc in patients with renal calculi.

Urine zinc (Zn) excretion was significantly higher in 338 male patients with renal calculi than in 21 normal male subjects, but there was no significant difference between 102 female patients with renal calculi and 15 normal female subjects. In 33 patients with renal calculi urinary Zn was less than 50% of the mean normal value; in these patients there is a possibility that lower urine Zn excretion contributes to the formation of renal calculi. Hydrochlorothiazide produced a striking and sustained increase in urinary Zn excretion, which might contribute to the efficacy of this drug in the prevention of calcific renal stones. Serum Zn levels remained normal in the majority of subjects on long term thiazide therapy, but the occasional finding of subnormal levels suggests that long term thiazide therapy carries with it the hazard of Zn deficiency.