Impact of standardization of creatinine methodology on the assessment of glomerular filtration rate in children.
There is a global effort to standardize clinical laboratory serum creatinine measurements to the reference method of isotope-dilution mass spectrometry (IDMS). Creatinine values in serum and urine are frequently used in children to calculate creatinine clearance (mCrCl) or estimate glomerular filtration rate (GFR) by Schwartz's equation (eGFR). The original normative data of mCrCl and eGFR were developed using Jaffe method. To investigate what impact the differences in methodologies of creatinine analysis will have on mCrCl and eGFR, we measured creatinine in random serum and urine samples by three commercially available assays: Jaffe (J), enzymatic (E) and enzymatic method traceable to IDMS (E-IDMS). There was a significant bias in the two enzymatic methods when compared with J method. The theoretical predicted errors in overestimating mCrCl ranged from 1.10 to 1.34 by E and 1.20 to 1.54 by E-IDMS; and in calculating eGFR 1.07-1.16 by E and 1.30-1.46 by E-IDMS, which was further confirmed in children who had formal GFR evaluation. Thus, as the clinical laboratories calibrate their creatinine assays to the gold standard IDMS method, it is important for the pediatric nephrology community to develop new equations for estimation of GFR based on the new creatinine assay.
Srivastava
Tarak
T
Section of Nephrology, University of Missouri at Kansas City, MO 64108, USA. tsrivastava@cmh.edu
Alon
Uri S
US
Althahabi
Randah
R
Garg
Uttam
U
D002138:Calibration; D002648:Child; D003404:Creatinine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis* / Q000378:metabolism; D007677:Kidney Function Tests / Q000592:standards*; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry / Q000592:standards*; D008954:Models, Biological; D011237:Predictive Value of Tests; D011865:Radioisotope Dilution Technique / Q000592:standards*; D019275:Radiopharmaceuticals; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D015203:Reproducibility of Results; D016284:Technetium Tc 99m Pentetate
D019275:Radiopharmaceuticals; D011933:Reagent Kits, Diagnostic; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate