Renal function damage in children with duplex kidneys

To evaluate renal function damage in children with duplex kidneys.

A total of 355 duplex kidneys, 110 urinary tract infection (UTI) kidneys without abnormalities, and 104 kidneys with primary unilateral vesicoureteral reflux (VUR) were reviewed. Clinical data including age at diagnosis, body weight, history of UTI, ureteroceles, ectopic ureteral opening, VUR grade, serum creatinine level, cystatin C level, renal scarring, split renal function in dimercaptosuccinic acid scans, and effective renal plasma flow (ERPF) were analyzed.

Duplex kidneys had a higher grade of VUR and renal scarring. Split renal function in unilateral duplex kidneys (45.58 ± 12.85%) was much lower than that in contralateral duplex kidneys (56.33 ± 11.90%) and controls (50.00 ± 11.38%) (P < 0.001 and P = 0.014, respectively). Both left and right split renal functions in bilateral duplex kidneys were similar to those ipsilateral to the controls (P = 0.906 and P = 0.932, respectively). However, the total ERPFs in the left, right, and bilateral duplex kidneys were significantly lower than that in the control group (P = 0.003, P = 0.001, and P = 0.003, respectively). The total ERPFs in the left and right unilateral duplex kidneys were similar. ERPF in unilateral duplex kidneys (106.70 ± 48.05 mL/min/m²) was significantly lower than that in contralateral duplex kidneys (150.18 ± 49.01 mL/min/m²) or those ipsilateral to controls (145.98 ± 41.16 mL/min/m²) (P < 0.001 and P < 0.001, respectively).

Duplex kidneys are usually accompanied by a higher grade of VUR, more severe renal scarring, and renal function impairment. Split renal function in duplex kidneys often declines significantly. Notably, the evaluation of split renal function in bilateral duplex kidneys should be performed cautiously.