DIFFERENTIAL EXCRETION OF URINARY PROTEINS IN CHILDREN WITH VESICOURETERAL REFLUX AND REFLUX NEPHROPATHY

We studied 40 children with a history of vesicoureteric reflux (VUR) w ithout evidence of renal scarring, 93 children with a history of VUR a nd renal scarring and 10 children with previous urinary tract infectio ns in whom the urinary tract was radiologically normal. Urine retinol- binding protein (RBP), albumin and N-acetyl-beta-D-glucosaminidase (NA G) were measured in each child. All were free from infection at the ti me of the analysis. Urinary RBP and NAG levels were significantly elev ated (P <0.001) in the group of children with renal scarring. Elevated RBP levels were detected in 51% of children with bilateral renal scar ring compared with 7% of children with unilateral scarring. Urine RBP excretion increased progressively according to the type of scarring, b est determined by the type of scarring of the less affected kidney. In children with renal scarring, elevated NAG levels were seen mostly in the 65 children with bilateral scarring and severe reflux. Urine albu min excretion was elevated in 10 children, 9 with bilateral scarring, all of whom had elevated RBP excretion. Urine protein excretion was un affected by the presence or absence of persisting VUR. There was a str ong negative correlation between glomerular filtration rate and RBP ex cretion (r = -0.69). We conclude that evidence of tubular dysfunction is common in children with bilateral renal scarring and usually preced es any glomerular protein leak. Tubular dysfunction may be the consequ ence of relative nephron hyperperfusion in the presence of bilateral s carring.