Vesicoureteric reflux in children.

Sir,

The study by Kari et al.[1] on vesicoureteric reflux (VUR) in children was read with interest. They concluded that children with primary VUR and normal bladder had a good prognosis with a normal kidney function, whereas children with secondary VUR associated with abnormal bladder caused by non-neurogenic bladder, spina bifida or posterior urethral valves had abnormal kidney functions. I presume that such conclusion ought to be considered to some extent cautiously. My assumption is based on the following two points. (1) Kari et al.[1] totally relied upon serum creatinine to assess the adequacy of renal function in their studied cohort with VUR. It is obvious that VUR has been associated, since the old times, with altered renal functions. Nevertheless, some functional parameters might be altered before glomerular filtration rate (GFR) deteriorates, such as maximum urinary osmolality (Uosm) and urinary excretion of microalbumin (MA). An interesting Spanish study recruiting 77 VUR children showed after follow-up no differences in Uosm values according to VUR grade. All children with Grade I and II VUR had a normal renal concentration test. A long-term concentration defect was observed in 15 children, six with Grade III, 8 with Grade IV and 1 with Grade V. Only 2 patients with normal dimercaptosuccinic acid (DMSA) had reduced Uosm. The Uosm had a direct correlation with GFR (r = 0.6; P < 0.001). Regarding urinary excretion of MA, elevated values were found in 11 children, one with Grade II, four with Grade III, and six with Grade IV. Only 4 patients with normal DMSA showed MA values over the normal range. A negative correlation between osmolality levels and MA/creatinine quotient was observed (r = 0.37; P < 0.001). In comparison with patients with normal DMSA, patients with bilateral scars showed significantly lower values of Uosm and GFR. The study concluded that at the end of the follow-up period, a defect of concentration capacity in 19.5% and increase of microalbuminuria in 14.3% of the VUR children were observed and that the observed renal tubular function deterioration was more in relation with the loss of renal parenchyma than the initial grade of VUR.[2] I, therefore, presume that serum creatinine alone might not be the precise laboratory biochemical parameter to assess renal function and hence, determining the prognosis of primary and secondary VUR as Kari et al.[1] proposed. (2) The functional outcomes have been linked on the presence or absence of renal scarring in VUR patients. Although those with bilateral scarring have a significantly lower creatinine clearance than those with unilateral scarring, the severity of scar grade alone does not always predict the overall creatinine clearance with short-term follow-up.[3]