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

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.

We measured (51)Cr-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).

The mean reference GFR was 76.77 +/- 17.01 ml/min/1.73 m(2). 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 m(2) and a precision of 12.57 ml/min/1.73 m(2). 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 m(2)). As for cystatin C-based equations, the Filler equation had the least bias (0.03 ml/min/1.73 m(2)) but low accuracy (78.43% within 30% of the reference).

We conclude that the IDMS-MDRD equation provided the best estimate of GFR in our early postoperative Korean renal transplant patients.