To assess renal function in the operated kidney at different time points post partial nephrectomy (PN) and establish the time in which optimal recovery occurs. Recovery of renal function post-PN has received significant attention. However, the optimal time to determine full recovery has not been clearly established.

Renal function following minimally invasive (laparoscopic and robotic) PNs performed between 2002 and 2015 was reviewed. Patients included in this study had renal function assessed preoperatively as well as 3 days, 6-12 weeks, and 1 year post-PN, using a combination of estimated glomerular filtration rate (eGFR) from serum creatinine and relative renal uptake (RRU) from Tc99m-MAG3 renal scintigraphy. Together, eGFR and RRU provide the ipsilateral renal function (IRF) of the operated organ.

At 6-12 weeks postoperatively, percent preserved eGFR, RRU, and IRF (relative to preoperative baselines) were 92.1%, 83.3%, and 77.4% respectively. %IRF at 6-12 weeks was significantly improved from %IRF at 3 days postoperatively, but did not differ significantly from 1 year postoperatively. Furthermore, 89% of patients had RRU values at 6-12 weeks which differed by less than 5% from RRU values at 1 year.

Our data suggest that renal function recovery at 6-12 weeks was equivalent to long-term recovery at 1 year in the majority of post-PN patients. This has important implications for post-PN follow-up, particularly in assessing the functional outcomes utilizing novel minimally invasive PN strategies, as well as in planning staged procedures for bilateral synchronous renal masses.