Excretion of urinary calcium and oxalate on three diets in patients with urolithiasis.

Effects of standard mineral, free, and low calcium--low oxalate diets on the urinary excretion of calcium and oxalate were studied in 153 consecutive patients with single or recurrent renal/ureteral stone. The patients were divided into four groups: 78 men with single stone (MS), 40 men with recurrent stone (MR), 30 women with single stone (WS), and 5 women with recurrent stone (WR). The urine volume was altered significantly (p less than 0.001) by the diet. The sex and the diet had a significant influence on the urinary excretion of calcium. The urinary excretion of oxalate was altered significantly by the diet (p less than 0.001), but not by sex nor by the number of stones. The goal for the low calcium--low oxalate diet (the simple concentration product under 26) was reached in MS and WS. The excretion of urinary calcium and oxalate increased and urine volume decreased in the samples collected at home when compared with the samples collected in the hospital. This was interpreted as a failure of the dietary regimen at home.