title: Detecting reduced renal function in children: comparison of GFR-models and serum markers.
abstract: BACKGROUND
  The aim of this study was to compare the ability of renal indicators [serum creatinine (SCr), cystatin C (SCysC)] and glomerular filtration rate (GFR)-models to discriminate normal and reduced renal function. As a single cut-off level will always lead to false classifications, we propose using two cut-off levels, dividing renal function into normal or reduced, with an intermediate "gray zone" of indeterminable results.
  
  
  METHODS
  Glomerular filtration rate was measured by plasma clearance of (51)Cr-EDTA (13.7-147.4 mL/min/1.73 m(2)) in 119 children (age range 2.3-14.9 years). Reduced renal function was defined as a GFR of  <82 mL/min/1.73 m(2). SCr, SCysC, age-normalized creatinine (SCr-ratio), and eight published GFR-models were compared for their ability to correctly classify renal function as normal or reduced. Cut-off levels were determined so as to give 99 % certainty outside the gray zone.
  
  
  RESULTS
  The multivariable GFR-models by Schwartz et al. (J Am Soc Nephrol 2009; 20:629-637) and Zappitelli et al. (Am J Kidney Dis 2006; 48:221-230) and two models by Andersen et al. [Am J Kidney Dis 2012; 59(1):50-57: body cell mass (BCM)-model and Weight-model] performed significantly better than all other variables (P < 0.01), with the BCM-model performing the best (P < 0.05). The SCr-based Schwartz formula and SCr-ratio both performed better than SCr and SCysC.
  
  
  CONCLUSIONS
  Among the 119 children enrolled in this study and the renal indicators tested, the BCM-model had the best diagnostic performance in terms of screening for normal or reduced renal function, and the SCr-ratio was a superior diagnostic tool to both SCr and SCysC.
authors.affiliation: Department of Nuclear Medicine, Aalborg Hospital, Aarhus University Hospital, Hobrovej 18-22, 9000 Aalborg, DK, Denmark. tba@rn.dk
authors.forename: Trine Borup
authors.initials: TB
authors.lastname: Andersen
authors.forename: Lars
authors.initials: L
authors.lastname: Jødal
authors.forename: Erland J
authors.initials: EJ
authors.lastname: Erlandsen
authors.forename: Anni
authors.initials: A
authors.lastname: Morsing
authors.forename: Jørgen
authors.initials: J
authors.lastname: Frøkiær
authors.forename: Jens
authors.initials: J
authors.lastname: Brøchner-Mortensen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis* / Q000503:physiopathology; D007677:Kidney Function Tests / Q000379:methods; D008297:Male
chemical_list: D055316:Cystatin C; D003404:Creatinine