Clinical Utility of Postoperative Day 1 Technetium‐99m Mercaptoacetyltriglycine Scintigraphy for Early Assessment of Graft Function in Living Donor Kidney Transplant Recipients

Background At our institution, 99mTc‐MAG3 renal scintigraphy is routinely performed preoperatively in living kidney donors and on postoperative Day 1 in recipients. Given the interindividual variability in MAG3 clearance, we hypothesized that postoperative MAG3 clearance could serve as an early indicator of renal graft function. In addition, we explored whether the donor‐to‐recipient clearance ratio (M‐ratio) provides supplemental clinical value. Early identification of such indicators of graft function is essential for optimizing postoperative management and improving outcomes. Methods This retrospective study analyzed 52 living donor kidney transplants performed between October 2009 and May 2024. Associations were examined between donor and recipient MAG3 clearance values, the M‐ratio (elevated ≥ 1.5 vs decreased/stable < 1.5), donor/recipient age and sex, T1/2 pattern (good excretion ≤ 20 min vs delayed > 20 min or unmeasurable), total ischemic time, graft weight, dialysis duration, and estimated glomerular filtration rate (eGFR) at 1 week and 1–12 months postoperatively. Variables with p < 0.05 in univariate analysis entered multivariate regression. Results Univariate analysis showed that recipient MAG3 clearance, the M‐ratio, donor and recipient age, T1/2 (up to 1 month), and graft weight (at 1 week) were significantly associated with graft function. In contrast, donor MAG3 clearance was not correlated with postoperative renal function. In multivariate analysis, recipient MAG3 clearance, recipient age, and graft weight remained independently associated with early graft function, whereas the M‐ratio lost significance. Conclusions Recipient MAG3 clearance on postoperative Day 1 is a practical, noninvasive indicator of renal graft function, while donor clearance and the M‐ratio are not independently associated with postoperative outcomes.