Long-Term Assessment of Kidney Function After Nephron-Sparing Surgery Using 99mTc-DMSA Scintigraphy: Is There a Marker for Predicting Split Renal Function?

Objectives To evaluate split renal function (SRF) using technetium-99m-dimercaptosuccinic acid ( 99m Tc-DMSA) scintigraphy after nephron-sparing surgery (NSS), and to identify clinical factors affecting SRF decline. Methods A retrospective analysis was conducted on open (n = 28) and laparoscopic (n = 18) NSS patients between 2018 and 2023 with at least 1 year of follow-up. Based on postoperative 99m Tc-DMSA, patients were divided into Group-1 (SRF ≤ 45%) and Group-2 (SRF > 45%). Patient’s demographics, tumor characteristics, and clinical parameters were compared. Results A total of 46-patient (26 males/20 females) with median 55 (25–71) years old were included. Group-1 had larger tumors (40 (12–106) vs. 26 (10–65) mm; p = 0.038), higher PADUA-score (7 (6–9) vs. 6 (6–8); p = 0.028), and longer operation time (180 (90–240) vs. 120 (60–240) min; p = 0.003). NSS without vascular clamping was more common in Group-2 (80.8% vs. 35%, p = 0.002). A significant GFR decline was noted in Group-1 (13.1 (8.1–27.1) vs. 6.1 (-6.2–9.3) ml/min/1.73 m²; p = 0.004). SRF was negatively correlated with tumor size (r=-0.458, p = 0.01), warm ischemia time (r=-0.355, p = 0.015), operation time (r=-0.458, p = 0.001), and hospital stay (r=-0.466, p = 0.001). A tumor size of 29 mm was identified as the optimal cut-off in the ROC-analysis to predict a decrease of SRF below 45% on 99m Tc-DMSA (AUC (CI:95%) = 0.68 (0.52–0.85); p = 0.038). Conclusions Long-term SRF decline after NSS appears to be associated with larger tumors and warm ischemia time. Particularly, our results suggest that tumor size ≥ 29 mm may be used as a potential predictor of SRF reduction below 45% on 99m Tc-DMSA.