Association of urinary sex steroid hormones with urinary calcium, oxalate and citrate excretion in kidney stone formers.

ABSTRACT

BACKGROUND: Sex-specific differences in nephrolithiasis with respect to both distribution of prevalence and stone composition are widely described and may be influenced by sex hormones. METHODS: We conducted a cross-sectional analysis of the relationship between 24-h urinary sex hormone metabolites measured by gas chromatography-mass spectrometry with urinary calcium, oxalate and citrate excretion in a cohort of 628 kidney stone formers from a tertiary care hospital in Switzerland, taking demographic characteristics, kidney function and dietary factors into account. RESULTS: We observed a positive association of urinary calcium with urinary testosterone and 17ß-oestradiol. Positive associations of urinary calcium with dehydroepiandrosterone (DHEA), 5α-DH-testosterone, aetiocholanolone, androsterone and oestriol were modified by net gastrointestinal alkali absorption or urinary sulphate excretion. As the only sex hormone, DHEA was inversely associated with urinary oxalate excretion in adjusted analyses. Urinary citrate correlated positively with urinary testosterone. Associations of urinary citrate with urinary androsterone, 17ß-oestradiol and oestriol were modified by urinary sulphate or sodium or by sex. CONCLUSIONS: Urinary androgens and oestrogens are significantly associated with urinary calcium and citrate excretion and associations are modified in part by diet. Our data furthermore reveal DHEA as a novel factor associated with urinary oxalate excretion in humans.