Longitudinal changes in renal parenchymal volume and function status after partial nephrectomy: a retrospective cohort study

Background: The ipsilateral renal parenchymal volume (RPV) experiences a sharp decrease shortly after partial nephrectomy (PN), mainly due to surgical remove or devascularization of kidney tissue. However, the subsequent change of RPV and its association with glomerular filtration rate (GFR) fast decline remains unknown. Our objective was to investigate the change of ipsilateral RPV and renal function status from new baseline (1–12 months after PN) to latest follow-up (≥1 year) after PN, and to explore factors associated with ipsilateral RPV decrease rate and correlation between RPV decrease and GFR fast decline. Materials and methods: A retrospective review of 367 patients with PN was conducted. Three-dimensional reconstruction of computed tomography (CT)/MRI images was performed for RPV calculation. Spectrum score was used to assess the degree of acute kidney injury (AKI) in the operated kidney after PN. GFR decline greater than 3 ml/min/1.73 m 2 /year was defined as GFR fast decline. One hundred fourteen patients underwent abdominal surgery was used as control. Predictive factors for subsequent decrease of RPV rate and GFR fast decline were evaluated by linear and logistic regression, respectively. Results: With a median interval time of 21.1 (interquartile range:13.8–35.5) months, median ipsilateral RPV significantly decreased from 118.7 (interquartile range:100.7–137.1) ml at new baseline to 111.8 (IQR: 92.3–131.3) ml at latest follow-up. The interval time [β: 1.36(0.71–2.01), P <0.001] and spectrum score [β: 5.83 (2.92–8.74), P <0.001] were identified as independent predictors of ipsilateral RPV decrease rate. GFR fast decline was observed in 101 (27.5%) patients. Annual ipsilateral RPV decrease rate [odds ratio:1.67 (1.05–2.67), P =0.03] and overweight [odds ratio:1.63 (1.02–2.60), P =0.04] were independent predictors of GFR fast decline. Conclusions: Ipsilateral RPV experienced a moderate but significant decrease during follow-up after PN, especially in those with severer acute kidney injury. The presence of GFR fast decline was found to be associated with reduction of ipsilateral RPV, particularly in overweight individuals.