title: Effect of Demographics on Excretion of Key Urinary Factors Related to Kidney Stone Risk.
abstract: OBJECTIVE
  To investigate the effect of demographics including age and sex on excretion of 4 key urinary factors (calcium [Ca], magnesium [Mg], oxalate and uric acid [UA]) related to kidney stone risk.
  
  
  METHODS
  Twenty-four-hour urine samples were collected from non-Hispanic white sibships in Rochester, MN. Height, weight, blood pressure, serum creatinine, and cystatin C were measured. Diet was assessed using the Viocare food frequency questionnaire. Effects of demographics and dietary elements on urinary excretions were evaluated in univariate, multivariate, and interaction models that included age, sex, and body mass index (BMI).
  
  
  RESULTS
  Samples were available from 709 individuals. In multivariate models, sex was a significant predictor of all 4 urinary factors, age was significant for all but UA excretion, and serum creatinine was significant only for Ca and Mg excretion (P <.05). BMI or weight positively correlated with Mg, oxalate, and UA excretion (P <.05). Use of a thiazide diuretic (lower) and dietary protein (higher) were associated with Ca excretion, whereas dietary Ca was associated with higher Mg excretion. Urinary UA excretion increased with animal protein intake and cystatin C estimated glomerular filtration rate (eGFR) and was lower with concurrent loop diuretic use. Significant interaction effects on urinary UA excretion were observed for loop diuretic use and sex, eGFR and sex, age and animal protein intake, and BMI and eGFR (P <.05).
  
  
  CONCLUSIONS
  Age and sex influence excretion of key urinary factors related to kidney stone risk and should be taken into account when evaluating kidney stone patients.
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Majuran
authors.initials: M
authors.lastname: Perinpam
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI; Institute for Social Research, University of Michigan, Ann Arbor, MI.
authors.forename: Erin B
authors.initials: EB
authors.lastname: Ware
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Smith
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Turner
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI.
authors.forename: Sharon L R
authors.initials: SL
authors.lastname: Kardia
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN; Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN. Electronic address: Lieske.John@mayo.edu.
authors.forename: John C
authors.initials: JC
authors.lastname: Lieske
mesh_terms: D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000652:urine*; D015992:Body Mass Index; D002129:Calcium Oxalate / Q000652:urine; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000453:epidemiology* / Q000209:etiology / Q000652:urine; D008274:Magnesium / Q000652:urine; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods*; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014527:Uric Acid / Q000652:urine
chemical_list: D015415:Biomarkers; D002129:Calcium Oxalate; D014527:Uric Acid; D008274:Magnesium