Sex specific factors in recurrent idiopathic calcium urolithiasis

: For question of sex dependency 24 h-urine samples of 165 patients with recurrent idiopathic calcium urolithiasis (100 men, 65 women) were obtained during regular diet and analyzed for differences in excretion rates of lithogenic and inhibitory constituents. Results were compared to values of 43 apparently healthy subjects (31 men, 12 women). Male stone patients revealed significantly higher excretion rates of lithogenic substances (calcium, uric acid, phosphate) and of the inhibitory agent magnesium than female patients. No differences were found for citrate and oxalate excretion values. Combination of an elevated rate of hyperuricosuria and significantly lower urine-pH in male patients results in a higher risk of stone formation in men. Similar differences between sexes were observed among controls but on a lower excretory level. Trying to explain the differing urinary excretion rates between sexes, the influence of sex differences in diet and body weight is discussed. An alteration of stone forming risk through action of sex hormones on urinary constitution appears unlikely.