Causes of diminished renal function in the affected kidney after partial nephrectomy.

To determine the cause of diminished renal function in the affected kidney after partial nephrectomy (PN) for renal tumour, we analyzed the relationship between operative data and postoperative recovery with respect to renal function. From May 2005 to December 2010, pre- and postoperative (1 week and 3 months after the procedure) renal function was evaluated by 99mTc- mercaptoacetyltriglycine clearance in 51 patients treated with open partial nephrectomy (OPN; n = 24) and laparoscopic partial nephrectomy (LPN; n = 27). LPN was performed via retroperitoneal (RPLPN; n = 14) or transperitoneal (TPLPN; n = 13) routes. Renal cooling was performed after renal hilar clamping in OPN and RPLPN, although not in TPLPN. There were 10 patients (two in OPN, six in TPLPN, two in RPLPN) who had diminished renal function in the affected kidney from 1 week to 3 months after PN. Warm ischaemia (versus cold ischaemia; P = 0.017) during renal hilar clamping resulted in diminished renal function. Using multivariate analysis, renal cooling influenced postoperative diminished renal function (P = 0.008). Successful preservation of renal function after PN depends on renal cooling during renal hilar clamping. Cold ischaemia for avoiding renal damage is recommended if renal hilar clamping is necessary for tumour extraction.