title: Sex Steroid Hormone Levels May Not Explain Gender Differences in Development of Nephrolithiasis.
abstract: OBJECTIVE
  To determine whether serum sex steroid hormone levels, or the subsequent change in those levels over time, represent a risk factor for the development of nephrolithiasis in men.
  
  
  METHODS
  We retrospectively identified patients participating in a long-term cohort study (Rochester Epidemiology Project) in Olmsted County, Minnesota. Patients had previously undergone baseline detailed clinical examination and sex steroid hormone studies, including estradiol, testosterone, and bioavailable testosterone. Patients were followed on a biennial basis. Records were then reviewed to assess for formation of nephrolithiasis.
  
  
  RESULTS
  We identified 684 patients, with a median follow-up for stone formation of 12.8 years. All 684 patients had measurement of testosterone, of which 78.9% were in normal range. Five hundred eighteen men had baseline-free testosterone, of whom 88.6% were normal. Three hundred seventy-one patients had baseline estradiol, of whom 88.7% were normal. One hundred two men (14.9%) were found to have stones, with 61 of those (59.8%) occurring before first hormone measurement and 41 (40.2%) occurring after. On multivariate analysis, there was no significant association of serum hormones with nephrolithiasis, although a trend toward higher baseline testosterone and stones was seen (odds ratio [OR] 1.29; 95% confidence intervals [CI] 0.71, 2.33). Using a time-to-event for incident stone formation, we found no significant association of baseline hormones or percentage change in hormone levels over time with risk of stones.
  
  
  CONCLUSIONS
  We found no significant association of sex steroid hormone levels with the risk of nephrolithiasis formation in men, although a weak trend toward an increased risk with elevated testosterone was seen.
authors.affiliation: 1 Department of Urology, Mayo Clinic , Rochester, Minnesota.
authors.forename: John Joseph
authors.initials: JJ
authors.lastname: Knoedler
authors.affiliation: 1 Department of Urology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Krambeck
authors.affiliation: 2 Department of Nephrology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Walter
authors.initials: W
authors.lastname: Astorne
authors.affiliation: 3 Division of Health Sciences Research, Mayo Clinic , Rochester, Minnesota.
authors.forename: Erik
authors.initials: E
authors.lastname: Bergstralh
authors.affiliation: 2 Department of Nephrology, Mayo Clinic , Rochester, Minnesota.
authors.forename: John
authors.initials: J
authors.lastname: Lieske
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004958:Estradiol / Q000097:blood*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D053040:Nephrolithiasis / Q000097:blood / Q000453:epidemiology*; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013739:Testosterone / Q000097:blood*
chemical_list: D012739:Gonadal Steroid Hormones; D013739:Testosterone; D004958:Estradiol