The evaluation of the development of compensatory hypertrophy in the same and opposite kidney over time in patients undergoing partial and total nephrectomy for renal tumor by computed tomography volumetry

Aim: The gold standard treatment of renal tumors is surgery, which can be performed as either partial or total nephrectomy. After nephrectomies, it is known that the remaining renal parenchyma increases in dimensions for compensation. However, there are few studies on the extent of compensation and about the factors affecting the compensation. In this study, we aimed to investigate the presence, changes (compensation), extent and correlation of the renal volume with the clinical parameters over time by measuring the pre-operative and post-operative renal volume revealed by CT in the patients undergoing partial or total nephrectomy for renal tumors. Material and Method: In this restrospective cohort study, pre-operative and post-operative renal volumes in 3 follow-up periods (between 6-12, 24-36, 48-60 months) were measured using CT volumetry in 21 partial neprectomy and 40 total nephrectomy patients.. The amount and percentage of the compensation were determined and its association with the pre-operative comorbidity factors were investigated. Findings: There was a high correlation between the investigators (p<0.001). In contralateral kidneys, the compensation after total nephrectomy was 15.48%, 17.47% and 18.65% respectively between 6-12, 24-36, 48-60 months while it was 3.3%, 8.49%, 3.95% respectively after partial nephrectomy. There was a statistically significant difference between the compensation rates in total and partial nephrectomies (p<0.05). In total nephrectomies, there was approximately 34% loss of volume compared to pre-operative kidney volume. In partial nephrectomies, there was a statistically significant loss of total renal volume by 6.53% in 6-12 months (p<0,018) and the volume loss was compensated in 24-36 months (1.36%, p>0.05). In total nephrectomy group, post-operative eGFR loss was higher than partial nephrectomy group, but mean eGFR levels remained above 60 mL/min. Preoperative renal volumes were lower in deteriorating patients (eGFR<60 mL/min) in the post-operative follow-up (p <0.05). Results: Measuring kidney volume is a feasible modality in daily practice. In total nephrectomy group, the compensation is higher compared to partial nephrectomy group. In our series, there was no correlation between the existing comorbidities and the compensation. Preoperative renal volume was measured in total nephrectomies and there was data indicating that it could be used to predict the deterioration after the first postoperative year. New studies with larger series of patients are needed for better conclusions.