Matched-pair analysis of renal function in the immediate postoperative period: a comparison of living kidney donors versus patients nephrectomized for renal cell cancer.

Purpose: Living kidney donation (LKD) involves little risk for the donor and provides excellent functional outcome for transplant recipients. However, contradictory data exist on the incidence and degree of impaired renal function (IRF) in the donor. Only few studies compared the incidence of IRF in donors with that of patients having undergone radical nephrectomy (RN).
Methods: From 1992 to 2012, 94 healthy subjects underwent an open nephrectomy for living kidney donation at the University Medical Center of Würzburg. These patients were compared with matched subjects who had the same surgical procedure for renal cell carcinoma at the Carl-Thiem Hospital Cottbus (1:1 matching using propensity scores).
Results: In the LKD-group, no complication ≥ Grade 3 according to the Clavien-Dindo classification occurred. Donors had a preoperative median estimated glomerular filtration rate (eGFR) of 85.1 ml/min which changed to 54.4, 57.0 and 61.0 ml/min (all p < 0.001 in comparison with baseline) on postoperative days 7-10, 365 and 730, respectively. While median eGFR between LKD- and RN-groups was nearly equal (85.1 vs. 85.3 ml/min; p = 0.786), median immediate postoperative eGFR was significantly lower in the LKD-group (54.3 vs. 60 ml/min; p = 0.002). Furthermore, in LKD, the percentage decrease compared with baseline was significantly higher (34.4 vs. 32 %; p = 0.017).
Conclusions: In living kidney donors, median eGFR decreased by 34.4 % immediately after surgery. Compared with matched RN-patients, immediate postoperative IRF is significantly more pronounced. One explanation may be that in kidney tumor patients, compensatory adaptive filtration activity of the contralateral kidney sets in already preoperatively.