Long-term functional evaluation of the treated kidney in a prospective series of patients who underwent laparoscopic partial nephrectomy for small renal tumors

Background: Renal scintigraphy may allow long-term monitoring of ischemic damage after partial nephrectomy (PN). Objective: Evaluate use of renal scintigraphy for evaluating long-term effects of warm ischemia on renal function in patients with a normal contralateral kidney. Design, setting, and participants: We prospectively examined kidney function of 54 patients who underwent laparoscopic PN (LPN). Minimum follow-up time was 4 yr. Intervention: LPN was performed with warm ischemia by transperitoneal or retroperitoneal approach. Measurements: Demographic, perioperative, and pathologic data and postoperative complications were registered. Split renal function (SRF) and effective renal plasma flow (ERPF) were evaluated by renal scintigraphy preoperatively, at 3 and 12 mo postoperatively, then yearly. Baseline weighted differentials (b-WDs) of both SRF and ERPF in the affected kidney were calculated between baseline condition and every time point. Multivariate linear regression was used to find independent variables for increased b-WDs at 3 and 48 mo. P values<0.05 were considered significant. Results and limitations: The SRF and ERPF of kidneys treated by LPN decreased significantly at month 3 and subsequently remained stable through the duration of follow-up. Conversely, neither serum creatinine nor estimated glomerular filtration rate changed significantly during follow-up. The regression model showed statistical significance at month 3 for warm ischemia time (WIT) and age, whereas at 48 mo, statistical significance was reached by WIT alone. No new onset of cardiovascular disease was registered. No evidence of local recurrence was recorded with computed tomography scan. Our study may be underpowered due to small sample size; however, this is one of the largest long-term prospective series using renal scintigraphy to evaluate the renal function after LPN. Conclusions: WIT contributes to irreversible kidney damage observed at month 3 that does not appear to worsen.