title: Urine stone risk factors in nephrolithiasis patients with and without bowel disease.
abstract: BACKGROUND
  The prevalence of nephrolithiasis among patients with bowel disease is higher than in the general population. We examined urine stone risk factors and clinical characteristics of these patients, contrasted with a large group of stone forming patients without systemic disease.
  
  
  METHODS
  A total of 180 patients with bowel disease were compared with a group of 2048 nephrolithiasis patients with calcium or uric acid stones and without systemic diseases. Bowel diseases included inflammatory bowel disease with and without bowel resections, bowel resections from cancer or trauma, and bypass procedures for obesity or hypercholesterolemia. Urine stone risk factors, stone rates, stone compositions, and creatinine clearance were measured.
  
  
  RESULTS
  Compared to ordinary stone forming patients, bowel patients formed stones higher in rate of recurrence and in uric acid content. Uric acid content was highest when colon surgery had occurred. Urine volumes were low among all bowel patients except those with a bypass. Average creatinine clearance values were low among all bowel patients. Urine oxalate excretion was modestly elevated after small bowel resection, but very high with bypass. Supersaturations were increased mainly by low urine volume and-for uric acid-low pH. Patients with no surgery were indistinguishable from routine stone formers.
  
  
  CONCLUSIONS
  Low urine volume and pH are the main stone-forming abnormalities in bowel disease patients. Hyperoxaluria is extreme after bypass, but only modest after small bowel surgery. In the absence of surgery, bowel disease patients with stones cannot be distinguished from common stone formers by comprehensive stone risk measurements.
authors.affiliation: Nephrology Program and Urology Program, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Joan H
authors.initials: JH
authors.lastname: Parks
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Worcester
authors.forename: R Corey
authors.initials: RC
authors.lastname: O'Connor
authors.forename: Fredric L
authors.initials: FL
authors.lastname: Coe
mesh_terms: D002129:Calcium Oxalate / Q000378:metabolism; D002130:Calcium Phosphates / Q000378:metabolism; D019343:Citric Acid / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000601:surgery; D007668:Kidney / Q000502:physiology; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009747:Nutritional Physiological Phenomena; D012307:Risk Factors; D017678:Sex Distribution; D014527:Uric Acid / Q000378:metabolism; D014545:Urinary Calculi / Q000453:epidemiology* / Q000378:metabolism; D014556:Urine
chemical_list: D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D002129:Calcium Oxalate; D014527:Uric Acid; D019343:Citric Acid; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D008274:Magnesium; C485829:calcium phosphate, dibasic, anhydrous