title: Analytical precision of the Urolizer  for the determination of the BONN-Risk-Index (BRI) for calcium oxalate urolithiasis and evaluation of the influence of 24-h urine storage at moderate temperatures on BRI.
abstract: BACKGROUND
  Since its first publication in 2000, the BONN-Risk-Index (BRI) has been successfully used to determine the calcium oxalate (CaOx) crystallization risk from urine samples. To date, a BRI-measuring device, the "Urolizer", has been developed, operating automatically and requiring only a minimum of preparation. Two major objectives were pursued: determination of Urolizer precision, and determination of the influence of 24-h urine storage at moderate temperatures on BRI.
  
  
  METHODS
  24-h urine samples from 52 CaOx stone-formers were collected. A total of 37 urine samples were used for the investigation of Urolizer precision by performing six independent BRI determinations in series. In total, 30 samples were taken for additional investigation of urine storability. Each sample was measured thrice: directly after collection, after 24-h storage at T=21 degrees C, and after 24-h cooling at T=4 degrees C. Outcomes were statistically tested for identity with regard to the immediately obtained results.
  
  
  RESULTS
  Repeat measurements for evaluation of Urolizer precision revealed statistical identity of data (p-0.05). 24-h storage of urine at both tested temperatures did not significantly affect BRI (p-0.05).
  
  
  CONCLUSIONS
  The pilot-run Urolizer shows high analytical reliability. The innovative analysis device may be especially suited for urologists specializing in urolithiasis treatment. The possibility for urine storage at moderate temperatures without loss of analysis quality further demonstrates the applicability of the BRI method.
authors.affiliation: Department of Urology, Friedrich-Schiller-University of Jena, Jena, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Berg
authors.forename: Robin
authors.initials: R
authors.lastname: Bechler
authors.forename: Norbert
authors.initials: N
authors.lastname: Laube
mesh_terms: D002129:Calcium Oxalate / Q000652:urine*; D006801:Humans; D015203:Reproducibility of Results; D012307:Risk Factors; D013048:Specimen Handling / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D016482:Urinalysis / Q000379:methods*; D052878:Urolithiasis / Q000652:urine*
chemical_list: D002129:Calcium Oxalate