Comparison of Risk Factors for the Development of Proteinuria After Radical Nephrectomy for Renal Cell Carcinoma

Purpose: We investigated compensatory structural hypertrophy and functional hyperfiltration in patients with renal cell carcinoma (RCC) after radical nephrectomy (RN) according to the presence of proteinuria.

Patients and methods: We retrospectively enrolled 471 patients who underwent RN for RCC between October 2005 and December 2013. These patients were divided into two groups according to the presence of postoperative proteinuria (trace or greater (≥1+) urine dipstick). We obtained computed tomography images before and 1 year after surgery to calculate the functional renal volume (FRV). The preoperative and postoperative Chronic Kidney Disease Epidemiology Collaboration equation-calculated glomerular filtration rates (CKD-EPI GFRs) per unit FRV (GFR/FRV) were used to calculate the degree of hyperfiltration.

Results: The mean patient age was 54.7±11.1 years, and the mean preoperative CKD-EPI GFR, FRV, and GFR/FRV were 89.3±13.3 mL/min/1.73 m², 357.2±71.8 cm³, and 0.26±0.05 mL/min/1.73 m²/cm³, respectively. The percentage reduction rate of the GFR was not significantly different according to the presence of proteinuria (normal: -28.5±11.6% vs proteinuria: -28.7±15%; p=0.902); however, the postoperative hypertrophic FRV in the remnant kidney was significantly different (normal: 17.5±9.1% vs proteinuria: 13.8±14.1%; p=0.001). Meanwhile, the change in the percentage rate of the GFR/FRV was not significantly different (normal: 21.1±23% vs proteinuria: 23.8±28.3%; p=0.324). Multivariate logistic regression analysis revealed that age (p=0.010) and the GFR/FRV (p<0.001) were significant predictors of postoperative proteinuria.

Conclusion: Compensatory structural hypertrophy and functional hyperfiltration are positive adaptations that reduce the occurrence of proteinuria.