title: Gender differences in seasonal variation of urine stone risk factors.
abstract: OBJECTIVE
  We determined whether men and women differ in urine stone risk factors during the 4 seasons of the year.
  
  
  METHODS
  Measurements from 28,498, 24-hour urines from stone forming patients prior to treatment were analyzed to determine whether monthly variation was significant and whether the sexes differed using ANOVA. Locations of supersaturation maxima were determined.
  
  
  RESULTS
  The 2 sexes showed modest sodium depletion in summer with a corresponding decrease in urine calcium but men showed a remarkable decrease in urine volume, causing high calcium oxalate supersaturation. Women had maximum calcium oxalate supersaturation in early winter because of decreasing urine volume and increasing urine calcium excretion. Urine pH was reduced in the 2 sexes during summer but the decrease was far more marked in men, who had a uric acid supersaturation spike.
  
  
  OBJECTIVE
  Overall the sexes differ markedly in the timing of stone risk. Men show a dual summer calcium oxalate and uric acid high risk, while women show a high early winter calcium oxalate high risk.
authors.affiliation: Nephrology Section, University of Chicago, Illinois, USA.
authors.forename: Joan H
authors.initials: JH
authors.lastname: Parks
authors.forename: Robert
authors.initials: R
authors.lastname: Barsky
authors.forename: Frederic L
authors.initials: FL
authors.lastname: Coe
mesh_terms: D002118:Calcium / Q000652:urine; D002129:Calcium Oxalate / Q000652:urine; D002130:Calcium Phosphates / Q000652:urine; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D012307:Risk Factors; D012621:Seasons; D012727:Sex Characteristics; D012737:Sex Factors; D012964:Sodium / Q000652:urine; D014545:Urinary Calculi / Q000453:epidemiology* / Q000652:urine; D014556:Urine
chemical_list: D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D002129:Calcium Oxalate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D012964:Sodium; C485829:calcium phosphate, dibasic, anhydrous; D002118:Calcium