Follow-up study of unilateral renal function after nephrectomy assessed by glomerular filtration rate per functional renal volume

BACKGROUND To evaluate the clinical usefulness of estimated glomerular filtration rate (eGFR) divided by functional renal volume (FRV) measured by three-dimensional image reconstruction (eGFR/FRV) for the prediction of functional outcomes after nephrectomy. METHODS Eighty-three patients who underwent nephrectomy were enrolled. The FRV of each patient was measured before surgery. Preoperative medical information on proteinuria, blood pressure, blood glucose level, body mass index (BMI), hemoglobin level and serum cholesterol level were also obtained. We evaluated the relationships between eGFR/FRV and each of these parameters before surgery. We also assessed the potential relationship between eGFR/FRV and the 3-year postoperative eGFR. Stepwise multiple regression analyses were conducted to elucidate independent factors. RESULTS The median FRV and eGFR were 310.15 cm3 and 79.0 ml/min/1.73 m² before surgery, respectively. The correlation between FRV and eGFR was statistically significant (r = 0.465, P < 0.001). The median eGFR/FRV was 0.24 ml/min/1.73 m²/cm³. Stepwise multiple regression analysis showed that the independent parameters (multiple correlation coefficient, r = 0.389, P = 0.031) associated with eGFR/FRV were proteinuria, BMI, age and hypertension. Proteinuria was statistically associated with eGFR/FRV, and the independent parameters (multiple correlation coefficient, r = 0.694, P < 0.001) associated with the 3-year postoperative eGFR were age, BMI and eGFR/FRV. The eGFR/FRV was statistically associated with the 3-year postoperative eGFR (r = 0.559, P < 0.001). CONCLUSION The present results demonstrated that patients with proteinuria are expected to have a lower eGFR/FRV than those without proteinuria. The present study also supports the notion that eGFR/FRV is the primary determinant of the long-term functional outcome after nephrectomy. It should be taken into consideration that patients with a low eGFR/FRV may develop chronic kidney disease after nephrectomy.