title: Variability in creatinine clearance (CCR) and KT/V due to different methods of calculating volume and CCR.
abstract: OBJECTIVE
  This study aimed to compare the correlations between KT/V and creatinine clearance (Ccr) calculated by different methods and to determine and compare the correlations between KT/V and Ccr.
  
  
  METHODS
  Nonrandomized, retrospective analysis of data.
  
  
  METHODS
  Continuous ambulatory peritoneal dialysis (CAPD) outpatient clinic in a teaching hospital.
  
  
  METHODS
  All patients were included for analysis if the data collection was complete for the calculations of KT/V and Ccr using five different methods.
  
  
  METHODS
  Volume of distribution for urea (V) was estimated by four methods: Watson nomogram, ideal body weight (IBW), actual body weight, and total body surface area. Ccr was determined by five methods: Dialysate Ccr was calculated by creatinine (Cr) uncorrected and corrected for the presence of glucose; urinary Ccr was calculated using urinary Cr alone and the average urinary clearance of urea and Cr; and by the Cockcroft and Gault method.
  
  
  METHODS
  Correlations between KT/V and Ccr.
  
  
  RESULTS
  Sixty-three data sets were collected from 52 CAPD patients. The correlations between weekly KT/V and Ccr normalized to 1.73 m2 body surface area were found to be highly variable from one method to another (r2 = 0.012 -0.494). For obese patients (20% above IBW), KT/V values obtained were more variable using the Watson nomogram compared to the IBW and BSA methods.
  
  
  CONCLUSIONS
  KT/V calculated using the Watson nomogram and the Ccr determined using average of urinary urea and creatinine clearance gave the best correlation (r2 = 0.49).
authors.affiliation: Albany College of Pharmacy, New York 12208, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Low
authors.forename: G R
authors.initials: GR
authors.lastname: Bailie
authors.forename: R
authors.initials: R
authors.lastname: Rasmussen
authors.forename: G
authors.initials: G
authors.lastname: Eisele
mesh_terms: D001824:Body Constitution; D001830:Body Surface Area; D003404:Creatinine / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D012189:Retrospective Studies; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea; D003404:Creatinine