Factors influencing renal function reduction after partial nephrectomy.

PURPOSE: We investigated factors determining the degree of functional reduction by measuring changes in individual renal function before and after partial nephrectomy.
MATERIALS AND METHODS: In 117 patients who underwent elective partial nephrectomy the glomerular filtration rate of the renal units with tumor from the diethylenetetramine pentaacetic acid renal scan was measured before and at a mean of 6.5 months after surgery. Kidney volume was calculated using computerized tomography. Of these patients 52 and 65 underwent open and laparoscopic partial nephrectomy, respectively. Satinsky clamps were used for renal artery-vein clamping in all patients. We analyzed patient, tumor and perioperative characteristics including surgical method with respect to changes in glomerular filtration rate.
RESULTS: Renal cell carcinoma was diagnosed in 101 (86.3%) patients. Between the laparoscopic and open partial nephrectomy groups significant differences were noted in tumor size (2.14 vs 3.72 cm, p <0.001) and warm ischemia time (33.5 vs 20.5 minutes, p <0.001). Reduction and percent reduction in glomerular filtration rate (13.3 vs 12.6 ml per minute per m(2), p = 0.662; 29.9% vs 33.2%, p = 0.337), and reduction and percent reduction in kidney volume (35.8 vs 36.4 cm(3), p = 0.886; 20.4% vs 24.0%, p = 0.151), respectively, were similar between the groups. On multivariate analysis renal volume reduction (%, p <0.0001) was the most significant, independent prognosticator for glomerular filtration rate reduction followed by polar location of the tumor (upper vs mid-lower pole, p = 0.012) and increasing age (p = 0.041).
CONCLUSIONS: Renal volume reduction, tumor location and patient age determine renal function after partial nephrectomy. In appropriate cases the laparoscopic method can show surgical and functional outcomes equivalent to those of the open method.