renal tubular functions in patients with posterior urethral valve

Objectives: the aim of this study was to evaluate tubular functions of posterior urethral valve patients with preserved glomerular functions. methods: a total of 25 children (ages 1 - 18) who underwent surgery for puv and had an estimated glomerular filtration rate ≥ 90 ml/min per 1.73m² on long term follow-up and age-matched 25 healthy controls were enrolled. blood and urine samples were collected to assess electrolyte reabsorption, proteinuria, enzymuria, urine acidification and concentration. results: even though microalbumin/creatinine ratio was higher in the patient group [1.00 (1.98) vs 0.31 (0.34) mg/gr creatinine, p = 0.005] none of the subjects had enzymuria, overt proteinuria or hyperphosphaturia. serum bicarbonate levels were lower and urinary ph higher in patients than the controls (23.2±2.1 vs. 24.6±1.9 mmol/l, p = 0.028 and 6.24±0.77 vs. 5.60±0.64, p = 0.004); furthermore, patients had lower urinary osmolality and density (525 ± 214 vs. 743 ± 194 mosm/l, p = 0.001 and 1011± 5.0 vs. 1016 ± 6.8, p = 0.005). when patients were compared among themselves according to presence or absence of renal scarring and when patients without renal scars were compared to healthy controls, similar findings persisted. conclusions: this study showed that during long-term follow-up of posterior urethral valve patients with normal glomerular filtration rates, even though proximal tubular functions do not seem to be impaired, acidification and concentration defects exist indicating distal tubulopathy.