Suitability of the IDMS-traceable MDRD equation method to estimate GFR in early postoperative renal transplant recipients

Background/Aims: Accurate measurement of glomerular filtration rate (GFR) is critical for the management of kidney transplant recipients. Comparison of creatinine and cystatin C in renal transplant recipients gave conflicting results. We aimed to compare the performance of creatinine- and cystatin C-based equations and creatinine clearance in 102 early postoperative Korean renal transplant patients. Methods: We measured 51Cr-EDTA clearance using a 2-compartment model and considered this the reference GFR. Then, we estimated GFR using 13 creatinine- and 7 cystatin C-based equations. Serum creatinine value was calibrated to isotope-dilution mass spectrometry (IDMS). Results: The mean reference GFR was 76.77 ± 17.01 ml/min/1.73 m2. The IDMS-traceable MDRD (IDMS-MDRD) equation had the highest accuracy (94.12 within 30% of the reference; 99.02 within 50% of the reference) with a bias of 0.33 ml/min/1.73 m2 and a precision of 12.57 ml/min/1.73 m2. The Mayo Clinic equation also performed well (92.16% within 30% of the reference; 99.02% within 50% of the reference; bias: –0.19 ml/min/1.73 m2). As for cystatin C-based equations, the Filler equation had the least bias (0.03 ml/min/1.73 m2) but low accuracy (78.43% within 30% of the reference). Conclusions: We conclude that the IDMS-MDRD equation provided the best estimate of GFR in our early postoperative Korean renal transplant patients.