*Purpose: Kidney function is central to donor evaluation and KDIGO guidelines recommend using estimated GFR (eGFR) for initial screening. A new creatinine-based CKD-EPI equation (’21 eGFR eq) without race is being incorporated in clinical practice, and therefore having GFR reference values based on age, gender and race for screening prospective living kidney donors is of clinical importance.

*Methods: We compared cold iothalamate GFR (iGFR) to eGFR derived from the ’21 eGFR eq which excludes the race factor and the 2009 CKD-EPI eq (’09 eGFR) in donors stratified by age, gender and race. We report the lowest 5^th percentile (P5) and the median (P50) GFR for each method to determine minimum accepted GFR for donation by donor’s age, gender and race. We also used an arbitrary cutoff of 80 ml/min/1.73m² to evaluate percent of black (AA) and non-AA donors below this cutoff.

*Results: We studied 832 donors at our institution b/w 2002 and 2021 with a median age of 44 yrs (IQR 35-52), 61% were female and 9.1% were AA. The median iGFR, ’09 eGFR, ’21 eGFR for all donors was 101 (IQR 92-112), 97 (86-107) and 100 (89-109) ml/min/1.73 m², respectively (Table 1). Overall, GFR decreases with older age independent of GFR method and is similar by gender. In contrast , the eGFR for AA and non-AA donors differs b/w the ’09 eGFR and ’21 eGFR (Table 2). Only 3.3% non-AA donors had an iGFR of <80 ml/min/1.73m², but 14.4% of non-AA donors were below this cutoff and 2.6% AA donors using the race-based equation ’09 eGFR. The new ‘21 eGFR eliminates this difference by equalizing the eGFRs between AA and non-AAs. With the new eq 9.9% of all donors would fall below a pre-determined screening cut off GFR value for further evaluation (9.8% of non-AA and 10.5% of AA donors). The P5 for AA donors decreased from 83 to 75 ml/min/1.73m² when using ’09 eGFR compared to the ’21 eGFR eq which makes it similar to the p5 of non-AA.

*Conclusions: Using the CKD-EPI 2021 equation, screening eGFR values should be adjusted for donor’s age but not gender or race. However, while the new equation eliminates the difference in eGFR b/w AA and non-AA, it overall underestimates iGFR thus screening values should be adjusted in order not to miss any potential donor with optimal measured GFR.

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