title: Similarity of urinary risk factors among stone-forming patients in five regions of the United States.
abstract: OBJECTIVE
  To compare urinary biochemical risk factors among stone-forming patients in the Southeast (SE) or "stone belt" versus four other regions of the United States.
  
  
  METHODS
  Prospective biochemical survey for regional comparisons.
  
  
  METHODS
  Referral-based nephrolithiasis clinics, urologists, nephrologists, and family practitioners.
  
  
  METHODS
  Consecutive sample of 3473 stone-forming patients who submitted 24-hour urine collections for biochemical analyses of stone-forming risk factors.
  
  
  METHODS
  None.  Subjects taking medication known to interfere with stone-forming risk factors were deleted from the final data compilation.
  
  
  RESULTS
  Overall, the mean values for each urinary parameter spanned a narrow range without significant difference between the five regions.  Among "metabolic" factors, 40% in the SE had hypercalciuria (> 6.25 mmol/d), compared to 35%-43% in other regions, and hyperuricosuria (> 4.2 mmol/d) was found in 16% in the SE versus 17%-19% elsewhere.  Among "environmental" factors, low urine volume ( < 2 L/d) was found in 77% patients in the SE compared to 69%-78% elsewhere, and high sodium was encountered in 27% in the SE versus 24%-29% elsewhere.  No differences were noted in occurrence of other abnormal risk factors:  hyperoxaluria, hypocitraturia, low pH, high sulfate, high phosphorus, or low magnesium.
  
  
  CONCLUSIONS
  Despite expected regional differences in nutritional and environmental influences, the results of this study showed a striking similarity in urinary biochemical risk factor profiles of stone-formers in all five regions of the United States.
authors.affiliation: Center in Mineral Metabolism and Clinical Research, University of Texas, Southwestern Medical Center, Dallas, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Harvey
authors.forename: K D
authors.initials: KD
authors.lastname: Hill
authors.forename: C Y
authors.initials: CY
authors.lastname: Pak
mesh_terms: D002118:Calcium / Q000652:urine; D002951:Citrates / Q000652:urine; D006801:Humans; D008274:Magnesium / Q000652:urine; D010070:Oxalates / Q000652:urine; D010758:Phosphorus / Q000652:urine; D012307:Risk Factors; D012964:Sodium / Q000652:urine; D015144:Southeastern United States; D013431:Sulfates / Q000652:urine; D014481:United States; D014527:Uric Acid / Q000652:urine; D016482:Urinalysis / Q000706:statistics & numerical data*; D014545:Urinary Calculi / Q000453:epidemiology* / Q000209:etiology
chemical_list: D002951:Citrates; D010070:Oxalates; D013431:Sulfates; D014527:Uric Acid; D010758:Phosphorus; D012964:Sodium; D008274:Magnesium; D002118:Calcium