Comparison of GFR measurement with a two-blood sample technique using [(99m)Tc]Tc-DTPA vs. creatinine-based equations in potential kidney donors

INTRODUCTION: Accurate determination of glomerular filtration rate (GFR) is crucial for selection of kidney donors. Nuclear medicine methods are considered accurate in measuring GFR but are not always easily available. The four-variable Modification of Diet in Renal Disease (MDRD4), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Full Age Spectrum (FAS) formulas are common equations for estimating GFR and are recommended for initial assessment of kidney donors. The aim of this study was to evaluate the performance of these GFR estimation equations compared with technetium-99m diethylenetriaminepentaacetic acid ([(99m)Tc]Tc-DTPA) clearance. METHODS: We compared GFR estimation by [(99m)Tc]Tc-DTPA clearance using a two-blood sample method with estimation by MDRD4, CKD-EPI, and FAS creatinine-based equations in a population of healthy potential kidney donors. RESULTS: A total of 195 potential kidney donors (68.2% female; mean age 49 years, range 21–75 years) were included in this study. Mean [(99m)Tc]Tc-DTPA measured GFR (mGFR) was 101.5 ± 19.1 mL/min/1.73 m(2). All three equations underestimated the GFR value measured by [(99m)Tc]Tc-DTPA (MDRD4: –11.5 ± 18.8 mL/min/1.73 m(2); CKD-EPI: –5.0 ± 17.4 mL/min/1.73 m(2); FAS: –8.3 ± 17.4 mL/min/1.73 m(2)). Accuracy within 30% and 10% of the measured GFR value was highest for CKD-EPI. CONCLUSION: The CKD-EPI equation showed better performance in estimating GFR in healthy potential kidney donors, proving to be a more accurate tool in the initial assessment of kidney donors. However, creatinine-based equations tended to underestimate kidney function. Therefore, GFR should be confirmed by another method in potential kidney donors.