title: Estimated glomerular filtration rate is a poor predictor of concentration for a broad range of uremic toxins.
abstract: OBJECTIVE
  The degree of chronic kidney disease (CKD) is currently expressed in terms of GFR, which can be determined directly or estimated according to different formulas on the basis of serum creatinine and/or cystatin C measurements (estimated GFR [eGFR]). The purpose of this study was to investigate whether eGFR values are representative for uremic toxin concentrations in patients with different degrees of CKD.
  
  
  METHODS
  Associations between eGFR based on serum cystatin C and different uremic solutes (mol wt range 113 to 240 D; determined by colorimetry, HPLC, or ELISA) were evaluated in 95 CKD patients not on dialysis (CKD stage 2 to 5). The same analysis was also applied for six other eGFR formulas.
  
  
  RESULTS
  There was a substantial disparity in fits among solutes. In linear regression, explained variance of eGFR was extremely low for most solutes, with eGFR > 0.4 only for creatinine. The other eGFR formulations gave comparably disappointing results with regard to their association to uremic solutes. Relative similarity in R(2) values per solute for the different eGFR values and the strong disparity in values between solutes suggest that the differences in R(2) are mainly due to discrepancies in solute handling apart from GFR.
  
  
  CONCLUSIONS
  eGFR is poorly associated with concentrations of all studied uremic toxins in patients with different degrees of CKD, correlates differently with each individual solute, and can thus not be considered representative for evaluating the accumulation of solutes in the course of CKD.
authors: Nephrology Section, Department of Internal Medicine, Ghent University Hospital, Ghent, Belgium. sunny.eloot@ugent.be
authors: Sunny
authors: S
authors: Eloot
authors: Eva
authors: E
authors: Schepers
authors: Daniela V
authors: DV
authors: Barreto
authors: Fellype C
authors: FC
authors: Barreto
authors: Sophie
authors: S
authors: Liabeuf
authors: Wim
authors: W
authors: Van Biesen
authors: Francis
authors: F
authors: Verbeke
authors: Griet
authors: G
authors: Glorieux
authors: Gabriel
authors: G
authors: Choukroun
authors: Ziad
authors: Z
authors: Massy
authors: Raymond
authors: R
authors: Vanholder
references: J Am Soc Nephrol. 2009 Nov;20(11):2305-13
references: 19833901
references: Clin Chem. 2000 Aug;46(8 Pt 1):1206-7
references: 10926911
references: Nephrol Dial Transplant. 2007 Feb;22(2):592-6
references: 17040995
references: J Hypertens. 2010 Jun;28(6):1234-42
references: 20486275
references: Kidney Int. 2008 May;73(10):1174-80
references: 18305466
references: Ann Intern Med. 2006 Aug 15;145(4):247-54
references: 16908915
references: Clin Chem. 1988 Nov;34(11):2264-7
references: 3141084
references: Kidney Int. 2009 May;75(10):1009-14
references: 19242501
references: Nephrol Dial Transplant. 2009 May;24(5):1429-35
references: 19059932
references: Am J Kidney Dis. 2008 Mar;51(3):395-406
references: 18295055
references: Clin J Am Soc Nephrol. 2009 Oct;4(10):1551-8
references: 19696217
references: Nephrol Dial Transplant. 2010 Apr;25(4):1183-91
references: 19914995
references: Kidney Int. 2006 May;69(10):1780-5
references: 16612331
references: Perit Dial Int. 2004 Mar-Apr;24(2):176-81
references: 15119639
references: Am J Kidney Dis. 2009 Nov;54(5):891-901
references: 19615803
references: J Am Soc Nephrol. 2008 May;19(5):863-70
references: 18287557
references: N Engl J Med. 2010 Aug 12;363(7):609-19
references: 20581422
references: Kidney Int. 2005 Jun;67(6):2089-100
references: 15882252
references: Kidney Int. 2004 Feb;65(2):442-51
references: 14717914
references: J Am Soc Nephrol. 2006 May;17(5):1466-71
references: 16611716
references: Lancet. 2003 Feb 8;361(9356):512-9
references: 12583961
references: Circulation. 2004 Jan 20;109(2):172-7
references: 14662708
references: J Nephrol. 2007 Sep-Oct;20(5):554-9
references: 17918140
references: Nephrol Dial Transplant. 2006 Aug;21(8):2152-8
references: 16702203
references: J Clin Invest. 1975 Jun;55(6):1142-52
references: 1133164
references: Am J Kidney Dis. 2002 Aug;40(2):339-47
references: 12148107
references: Kidney Int. 2006 Mar;69(6):1081-7
references: 16421516
references: N Engl J Med. 2006 Jun 8;354(23):2473-83
references: 16760447
references: Pediatr Nephrol. 2003 Oct;18(10):981-5
references: 12920638
references: Kidney Int. 1992 Jun;41(6):1707-12
references: 1501426
references: Nephron. 1976;16(1):31-41
references: 1244564
references: J Am Soc Nephrol. 1999 Aug;10(8):1815-23
references: 10446951
references: Diabetes Care. 2006 May;29(5):1024-30
references: 16644632
references: J Thromb Haemost. 2006 Mar;4(3):566-73
references: 16405517
references: Nephrol Dial Transplant. 2008 Jun;23(6):1892-901
references: 18334529
references: Am J Kidney Dis. 2002 Feb;39(2 Suppl 1):S1-266
references: 11904577
references: Kidney Int. 2006 Jan;69(2):399-405
references: 16408133
references: Lancet. 2001 Dec 22-29;358(9299):2113-7
references: 11784625
references: J Am Soc Nephrol. 1995 Oct;6(4):1313-7
references: 8589304
references: J Am Soc Nephrol. 2008 Feb;19(2):388-95
references: 18199801