Compensatory renal growth in children with unilateral renal tumor treated by nephron-sparing surgery or nephrectomy

Introduction: In children with an unilateral renal tumor, nephron-sparing surgery (NSS) results in a more adequate renal function adaptation compared to nephrectomy. In the present study, we investigated whether nephron-sparing surgery is followed by a different renal structure adaptation compared to nephrectomy. Methods: Sixteen patients with unilateral renal tumor treated by nephrectomy (Group 1) and 10 treated by nephron-sparing surgery (Group 2) were enrolled in the study. Kidney volume was estimated by ultrasonography, using the formula for a prolate ellipsoid. Kidney volume was adjusted to the patient's weight and kidney laterality and expressed as a percentage of the expected volume of two kidneys in a healthy child. Total kidney volume (TKV) corresponded to the volume of the contralateral kidney in Group 1 patients, and to the volume of contralateral kidney + kidney remnant in Group 2 patients. Renal function was evaluated by serum creatinine values adjusted for sex and age and expressed as standard deviation scores (SDS). Results: Group 2 patients presented with a greater indexed TKV compared to Group 1 patients, (97.4 ± 18.8% vs. 77.0 ± 17.7%; p = 0.005). Indexed TKV below the reference range for healthy controls with two kidneys was found in 4 of 10 Group 2 patients vs. 14 of 16 Group 1 patients (p = 0.017). In both patient groups, correlation analysis of indexed TKV and creatinine SDS showed a negative correlation (r = -0.47; p = 0.01). Conclusion: In children with unilateral renal tumor, NSS is followed by a more adequate compensatory restoration of TKV compared with nephrectomy.