Excretion of urinary phosphate and magnesium on three diets in patients with urolithiasis.

The effects of standard mineral, free, and low calcium -- low oxalate diets on the urinary excretion of phosphate and magnesium were studied in 153 consecutive patients with single or recurrent renal or ureteric stones. The patients were divided in to four groups: 78 men with single stones (MS), 40 men with recurrent stones (MR), 30 women with single stones (WS) and five women with recurrent stones (WR). Men excreted significantly more phosphate and magnesium in the urine than women. The excretion of urinary phosphate and magnesium varied most for MS and least for WS. The high excretion of urinary phosphate on free diet together with infected urine probably accounted for the formation of stone in women with recurrent stones. The role of the dietary prevention of calcium urolithiasis was discussed.