MDRD or CKD-EPI for glomerular filtration rate estimation in living kidney donors

The evaluation of the measured Glomerular Filtration Rate (mGFR) or estimated Glomerular Filtration Rate (eGFR) is key in the proper assessment of the renal function of potential kidney donors. We aim to study the correlation between glomerular filtration rate estimation equations and the measured methods for determining renal function.

We analysed the relationship between baseline GFR values measured by Tc-⁹⁹m-DTPA (diethylene-triamine-pentaacetate) and those estimated by the four-variable Modification of Diet in Renal Disease (MDRD4) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in a series of living donors at our institution.

We included 64 donors (70.6% females; mean age 48.3±11 years). Baseline creatinine was 0.8±0.1 mg/dl and it was 1.1±0.2 mg/dl one year after donation. The equations underestimated GFR when measured by Tc⁹⁹m-DTPA (MDRD4-9.4 ± 25ml/min, P<.05, and CKD-EPI-4.4 ± 21ml/min). The correlation between estimation equations and the measured method was superior for CKD-EPI (r=.41; P<.004) than for MDRD4 (r=.27; P<.05). eGFR decreased to 59.6±11 (MDRD4) and 66.2±14ml/min (CKD-EPI) one year after donation. This means a mean eGFR reduction of 28.2±16.7 ml/min (MDRD4) and 27.31±14.4 ml/min (CKD-EPI) at one year.

In our experience, CKD-EPI is the equation that better correlates with mGFR-Tc⁹⁹m-DTPA when assessing renal function for donor screening purposes.