Study Type – Prognosis (case series) Level of Evidence 4 What's known on the subject? and What does the study add? At present, many studies have been executed to identify predictors for chronic kidney disease or renal insufficiency after radical nephrectomy or partial nephrectomy. We examined whether preoperative kidney volume is a predictor for renal function after radical or partial nephrectomies in RCC patients. To our knowledge, this is the first study to report on the relationship between preoperative kidney volume and changes in renal function in RCC patients who underwent radical nephrectomy or partial nephrectomy performed by one surgeon. OBJECTIVE: To investigate whether preoperative kidney volume is a prognostic factor for predicting the postoperative glomerular filtration rate (GFR) in renal cell carcinoma (RCC) patients. PATIENTS AND METHODS: We included 133 patients who underwent radical ( n = 83) or partial ( n = 50) nephrectomy for RCC. Kidney parenchymal volume was measured using personal computer‐based software and GFR was estimated before and after surgery at 6 and 12 months. We evaluated the change in kidney volume after radical and partial nephrectomy and used regression analysis to identify predictors of lower post‐surgical GFR at 12 months. RESULTS: The mean volume of the normal side kidney for the radical nephrectomy group increased from 142.4 mL to 166.0 mL (17.2%) and 171.5 mL (21.2%) after surgery at 6 and 12 months, respectively. In the partial nephrectomy group, the volume of the normal side kidney increased from 127.2 mL to 138.8 mL (9.1%) and 140.6 mL (10.9%) after surgery at 6 and 12 months, respectively. The volume of the operated side kidney decreased from 128.5 mL to 102.3 mL (20.1%) and 101.8 (20.6%) after surgery at 6 and 12 months, respectively. In the radical nephrectomy group, older age ( P < 0.001), preoperative volume of the normal kidney ( P = 0.022) and preoperative GFR for the normal side kidney ( P = 0.045) were significant predictors of lower post‐surgical GFR at 12 months. In the partial nephrectomy group, older age ( P = 0.001) and preoperative volume for both kidneys ( P = 0.037) were significant predictors of lower post‐surgical GFR at 12 months. CONCLUSION: Preoperative kidney volume is an independent predictor of GFR in RCC patients who underwent radical or partial nephrectomy.

We measured kidney volume using software and investigated the relationship between kidney volume and renal function. Age, gender, height, body weight, body mass index, body surface area and serum creatinine were recorded for 539 normal individuals. A tissue segmentation tool program was used to measure kidney volume from computerized tomography images. The glomerular filtration rate was calculated using the Cockcroft-Gault equation and an abbreviated modification of diet in renal disease equation. We looked for correlations of renal parenchymal volume with age and anthropometric measurements. We also tested for a correlation between kidney volume and renal function using the glomerular filtration rate according to the Cockcroft-Gault and modification of diet in renal disease equations. Mean kidney volume in all participants was 261.3 ± 58.1 ml. Mean volume in men was approximately 14 ml greater than in women (266.1 vs 251.8 ml, p = 0.004). Kidney volume correlated significantly with height (r = 0.344, p <0.001), body weight (r = 0.343, p <0.001), body mass index (r = 0.177, p <0.001), body surface area (r = 0.371, p <0.001) and age (r = -0.418, p <0.001). Kidney volume also correlated with the glomerular filtration rate according to the Cockcroft-Gault and modification of diet in renal disease equations (p <0.001, r = 0.615 and p <0.001, r = 0.432, respectively). Kidney volume and the glomerular filtration rate decreased in parallel with increasing age. Kidney volume correlates well with renal function and anthropometric measurements. Knowledge of these relationships will be valuable in clinical urology and nephrology.

To our knowledge the effects of preoperative kidney volume in living donors on the post-donation change in size and function of the remaining kidney have not been investigated. We studied the association between preoperative kidney volume, and volume change and delayed kidney function recovery in donors. From 2007 to 2008 we investigated 222 living donors. Kidney volume before and 6 months after surgery was estimated using the voxel count method. We analyzed correlations of kidney volume with patient characteristics, kidney function and actual kidney weight. To identify predictors of the volume increase of the remaining kidney and predictors of delayed kidney function recovery we performed regression analysis. Mean +/- SD total kidney volume was 311.9 +/- 50.6 cc and it correlated with weight, body surface area and kidney function (p <0.001). The mean volume increase in the remaining kidney was 27.6% +/- 9.7% (range 4.5% to 66.1%). Younger age (p <0.001) and lower preoperative volume of the remaining kidney (p = 0.019) were significant predictors of a greater increase in kidney volume on multiple linear regression analysis. Older age (OR 1.07, p <0.001), higher body mass index (OR 1.20, p = 0.008), lower preoperative kidney volume of the remaining kidney (OR 0.98, p = 0.003) and a lower preoperative diethylenetetramine pentaacetic acid glomerular filtration rate in the remaining kidney (OR 0.95, p = 0.017) were significant predictors of delayed kidney function recovery on multiple regression analysis. Kidney volume measured by the voxel count method was accurate and correlated with kidney function. Preoperative kidney volume is an independent predictor of the volume increase and delayed kidney function recovery in donors that could be used clinically.