Accuracy of GFR predictive equations using ID-MS traceable creatinine: compensated Jaffe and enzymatic

Abstract

Background: New ID-MS traceable creatinine kits including enzymatic creatinine (e-creat) and compensated Jaffe (j-creat) has been developed by Olympus.

Methods: Analytical performances of these reagents were tested on an AU 640 analyzer. A comparison study was performed against the method used in our laboratory (Randox creatinine enzymatic). Values of the glomerular filtration rate estimated (eGFR) from ID-MS traceable equation were compared to the GFR measured (mGFR) by a reference isotope method in a kidney transplant cohort.

Results: Total intra- and inter-assay variation coefficients were below 4%. Creatinine values were correlated with the Randox enzymatic method (e-creat = 0.98 Randox - 0.48 and j-creat = 0.99 Randox - 1.44, r2 = 0.98). Values of eGFR obtained with both e-creat and j-creat were well correlated to mGFR in our population of renal transplants.

Conclusions: The new ID-MS traceable methods improved estimation of GFR by predictive equations. However, the limitation of the Jaffe method in specific populations such as paediatric and elderly patients needs further investigations.