title: Urinary lithogenesis risk tests: comparison of a commercial kit and a laboratory prototype test.
abstract: OBJECTIVE
  Renal stone formation is a multifactorial process depending in part on urine composition. Other parameters relate to structural or pathological features of the kidney. To date, routine laboratory estimation of urolithiasis risk has been based on determination of urinary composition. This process requires collection of at least two 24 h urine samples, which is tedious for patients. The most important feature of urinary lithogenic risk is the balance between various urinary parameters, although unknown factors may be involved. The objective of this study was to compare data obtained using a commercial kit with those of a laboratory prototype, using a multicentre approach, to validate the utility of these methods in routine clinical practice.
  
  
  METHODS
  A simple new commercial test (NefroPlus®; Sarstedt AG & Co., Nümbrecht, Germany) evaluating the capacity of urine to crystallize calcium salts, and thus permitting detection of patients at risk for stone development, was compared with a prototype test previously described by this group. Urine of 64 volunteers produced during the night was used in these comparisons. The commercial test was also used to evaluate urine samples of 83 subjects in one of three hospitals.
  
  
  RESULTS
  Both methods were essentially in complete agreement (98%) with respect to test results. The multicentre data were: sensitivity 94.7%; specificity 76.9%; positive predictive value (lithogenic urine) 90.0%; negative predictive value (non-lithogenic urine) 87.0%; test efficacy 89.2%.
  
  
  CONCLUSIONS
  The new commercial NefroPlus test offers fast and cheap evaluation of the overall risk of development of urinary calcium-containing calculi.
authors.affiliation: Laboratory of Renal Lithiasis Research, University Institute of Health Sciences Research, University of Balearic Islands, Palma de Mallorca, Spain.
authors.forename: Félix
authors.initials: F
authors.lastname: Grases
authors.forename: Antonia
authors.initials: A
authors.lastname: Costa-Bauzá
authors.forename: Rafel M
authors.initials: RM
authors.lastname: Prieto
authors.forename: Miguel
authors.initials: M
authors.lastname: Arrabal
authors.forename: Tomás
authors.initials: T
authors.lastname: De Haro
authors.forename: Juan A
authors.initials: JA
authors.lastname: Lancina
authors.forename: Carmen
authors.initials: C
authors.lastname: Barbuzano
authors.forename: Sergi
authors.initials: S
authors.lastname: Colom
authors.forename: Joaquín
authors.initials: J
authors.lastname: Riera
authors.forename: Joan
authors.initials: J
authors.lastname: Perelló
authors.forename: Bernat
authors.initials: B
authors.lastname: Isern
authors.forename: Pilar
authors.initials: P
authors.lastname: Sanchis
authors.forename: Antonio
authors.initials: A
authors.lastname: Conte
authors.forename: Fernando
authors.initials: F
authors.lastname: Barragan
authors.forename: Isabel
authors.initials: I
authors.lastname: Gomila
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D018570:Risk Assessment; D052878:Urolithiasis / Q000175:diagnosis* / Q000652:urine*
chemical_list: D011933:Reagent Kits, Diagnostic