Objectives: Vesicoureteral reflux (VUR) has been associated, since the old times, with chronic renal failure (CRF). Nevertheless, some functional parameters may be altered before glomerular filtration rate deteriorates, such as maximum urinary osmolality (Uosm) and urinary excretion of microalbumin.
Methods: We retrospectively studied the records of 77 children (37 males and 14 females; 48% and 52% respectively) with the diagnosis of VUR that were cured at the time of the study and were two years old or older (6.28 +/- 3.75; range: 2-16 years). In addition to Uosm and urinary excretion of microalbumin, the grade of VUR, creatinine levels, GFR, and morphological anomalies detected in 99Tc dimercaptosuccinate gammagrams (DMSA) were collected.
Results: Only four patients had moderate CREF. No differences in Uosm values were observed 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 DMSA had reduced Uosm. Uosm had a direct correlation with GFR (r = 0.6; p < 0.001). Regarding urinary excretion of microalbumin, elevated values were found in 11 children, one with grade II, four with grade III, and six with grade IV. Only four patients with normal DMSA showed microalbumin values over the normal range. A negative correlation between osmolality levels and microalbumin/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.
Conclusions: At the end of the follow-up period we observed a defect on concentration capacity in 19.5% and increase of microalbuminuria in 14.3% of the children with the diagnosis of VUR. The frequency of CRF in our series is very low (5.1%). The observed renal tubular function deterioration is more in relation with the loss of renal parenchyma than the initial grade of VUR.