Contralateral kidney volume change as a consequence of ipsilateral parenchymal atrophy promotes overall renal function recovery after partial nephrectomy

Abstract

To evaluate whether ischemic time is related to ipsilateral parenchymal atrophy (IPA) and contralateral compensational hypertrophy (CCH) and how CCH affects late functional outcome after partial nephrectomy.

Parenchymal kidney volumes and glomerular filtration rate (GFR) were determined preoperatively and at 3, 6, and 12 months postoperatively in 79 patients. Kidney volume was measured by Voxel Plus(A (R)) 2.5 with a tissue segmentation tool. Correlation analysis and univariate and multivariate regression models were used to evaluate the recovery of IPA, CCH, and GFR.

The mean preserved ipsilateral kidney volume was 86.7 %. At 12 months, mean IPA and CCH were 3.0 and 4.8 %, respectively, and the mean GFR decrease was 8.0 %. Ipsilateral volume decrease and contralateral volume increase were significant until 6 months postoperatively (p < 0.05, for each). IPA and CCH were greater with a longer ischemic time (> 35 min; p = 0.029 and 0.003, respectively), and CCH correlated positively with IPA (r (2) = 0.052, p = 0.045). On multivariate analysis, IPA correlated with a longer ischemic time and percent of preserved normal parenchymal volume (PPV), and CCH correlated with a longer ischemic time, IPA, PPV, and total parenchymal volume increase. At 12 months postoperatively, CCH correlated with GFR recovery (r (2) = 0.072, p = 0.026), and significant predictors of GFR recovery were age, sex, PPV, and CCH.

We present the meaningful possibility that longer ischemic time and less preservation of normal parenchyma cause greater parenchymal atrophy, thereby promoting CCH, which contributes to renal function recovery after partial nephrectomy.