Volume and function of the operated kidney after nephron-sparing surgery for unilateral renal tumor.

Aim: We sought to assess the magnitude of functional decline and the natural history of the operated kidney residual function after zero-ischemia nephron-sparing surgery (Z-NSS) in children with unilateral renal tumor (URT).

Patients And Methods: 50 children were treated for URT at our surgical unit between 1992 and 2016. Of these 12 who underwent Z-NSS were available for the current analysis. Operated kidney function was assessed by 99mTc-dimercapto-succinic acid (DMSA) renal scintigraphy. Operated kidney volume was assessed by renal ultrasonography.

Results: A positive correlation between split renal function and split renal volume was found (P = 0.001). The subset of patients with ≥40% preservation of operated kidney function/volume (OKF/V) had no-time dependent changes during adolescence. The subset of patients with <40% OKF/V preservation had a catch-up growth that after puberty reached values not much different from those with ≥40% OKF/V preservation. At 5 years of follow-up, 3 of 5 patients with baseline dysfunction (eGFR between 40.8 and 89.4 ml/min/1.73 m) presented with a global renal function within normal range. After puberty, all patients presented with global renal function within normal values (eGFR between 95 and 151 ml/min/1.73 m).

Conclusions: In children with URT who underwent Z-NSS, the pattern of OKF/V recovery suggests that compensatory catch-up growth capacity during childhood minimizes OKF/V decline more than Z-NSS.

Level Of Evidence: Level I prognosis study - prospective cohort study with >80% follow-up and all patients enrolled at same time point in disease.