title: KDIGO 2012 Clinical Practice Guideline CKD classification rules out creatinine clearance 24 hour urine collection?
abstract: OBJECTIVE
  The recent guideline for the evaluation and management of Chronic Kidney Disease recommends assessing GFR employing equations based on serum creatinine; despite this, creatinine clearance 24-hour urine collection is used routinely in many settings. In this study we compared the classification assessed from CrCl (creatinine clearance 24h urine collection) and e-GFR calculated with CKD-EPI or MDRD formulas.
  
  
  METHODS
  In this retrospective study we analyze consecutive laboratory data: creatinine clearance 24h urine collection, serum creatinine and demographic data such as sex and age from 15,777 patients >18 years of age collected from 2011 to 2013 in our laboratory at Careggi Hospital. The results were then compared to the estimated GFR calculated with the equations according to the recent treatment guidelines. Consecutive and retrospective laboratory data (creatinine clearance 24h urine collection, serum creatinine and, demographic data such as sex and age) from 15,777 patients >18 years of age seen at Careggi Hospital were collected.
  
  
  RESULTS
  Comparison between e-GFR calculated with CKD-EPI or MDRD formulas and GFR according CrCl determinations and bias [95% CI] were 11.34 [-47,4/70.1] and 11.4 [-50.2/73] respectively. The concordance for 18/65 years aged group when compared with e-GFR classification between MDRD vs CKDEPI, MDRD vs CrCl and CKD-EPI vs CrCl were 0.78, 0.34, and 0.41 respectively, while in the 65/110years aged group the concordance Kappas were 0.84, 0.38, and 0.36 respectively.
  
  
  CONCLUSIONS
  The use of CrCl provides a different classification than the estimation of GFR using a prediction equation. The CrCl is unreliable when it is necessary to identify CKD subjects with decrease of GFR of 5ml/min/1.73m(2)/year.
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy. Electronic address: a.ognibene@med.unifi.it.
authors.forename: A
authors.initials: A
authors.lastname: Ognibene
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Grandi
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Lorubbio
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Rapi
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Salvadori
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Terreni
authors.affiliation: Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Veroni
mesh_terms: D000328:Adult; D000368:Aged; D003404:Creatinine / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000145:classification* / Q000503:physiopathology / Q000652:urine; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D003404:Creatinine
keywords: CKD-EPI; Chronic Kidney Disease; Creatinine; Creatinine clearance; Estimation GFR; Glomerular Filtration Rate; MDRD