Double-Blind Study with Thiazide in Recurrent Calcium Lithiasis

Abstract

The effect of 25 mg hydrochlorothiazide twice daily on the metaphylaxis of recurrent Ca lithiasis was compared to placebo in a double-blind study during 1 yr in 51 patients. A distinct and continuous decrease in urinary Ca excretion occurred only in patients given hydrochlorothiazide. Both groups showed a slight increase in total serum Ca levels, unchanged values for ionized and ultrafilterable Ca, and decreased urinary excretion of oxalate during the study. The activity products of Ca oxalate and Ca phosphate also were decreased in both groups but remained within the metastable range. Spontaneous passage of renal stones occurred during treatment in 6 patients given placebo and in 6 treated with hydrochlorothiazide, despite decreased urinary Ca excretion in the latter group. Evidently, the specific effect of hydrochlorothiazide treatment is a decrease in urinary Ca excretion in patients with Ca lithiasis, while other changes appear to be nonspecific effects of treatment.