title: Intestinal oxalate absorption is higher in idiopathic calcium oxalate stone formers than in healthy controls: measurements with the [(13)C2]oxalate absorption test.
abstract: OBJECTIVE
  We assessed the importance of oxalate hyperabsorption for idiopathic calcium oxalate urolithiasis, oxalate absorption in healthy volunteers and recurrent calcium oxalate stone formers was compared.
  
  
  METHODS
  The [(13)C2]oxalate absorption test, a standardized, radioactivity-free test, was performed. On 2 days 24-hour urine was collected and an identical standard diet containing 800 mg Ca daily was maintained. On the morning of day 2 a capsule containing 0.37 mmol sodium [(13)C2]oxalate was ingested. A total of 120 healthy volunteers (60 women and 60 men) and 120 patients (30 women and 90 men) with idiopathic CaOx urolithiasis (60% or greater CaOx) were tested.
  
  
  RESULTS
  Mean intestinal oxalate absorption in the volunteers was 8.0 +/- 4.4%, and in the patients was 10.2 +/- 5.2% (p <0.001). There was no significant difference in mean absorption values between men and women within both groups. A high overlap between the absorption values of volunteers and patients was found. Only in the patient group did absorption values greater than 20% occur. Oxalate absorption correlated with oxalate excretion in the patients, r = 0.529 (p <0.01) and in the volunteers, r = 0.307 (p <0.01).
  
  
  CONCLUSIONS
  In high oxalate absorbers dietary oxalate has a significant role in oxalate excretion and, therefore, increases the risk of calcium oxalate stone formation.
authors.affiliation: Department of Urology (Division of Experimental Urology), University of Bonn, Bonn, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Voss
authors.forename: Albrecht
authors.initials: A
authors.lastname: Hesse
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Zimmermann
authors.forename: Tilman
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: Gerd E
authors.initials: GE
authors.lastname: von Unruh
mesh_terms: D000293:Adolescent; D000328:Adult; D002129:Calcium Oxalate / Q000032:analysis*; D002247:Carbon Isotopes; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D010070:Oxalates / Q000378:metabolism*; D014545:Urinary Calculi / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D010070:Oxalates; D002129:Calcium Oxalate