Tubular urinary enzymes in acute post-infectious glomerulonephritis

Tubular function of 17 pediatric patients with a mild form of acute post-in fectious glomerulonephritis was prospectively evaluated by assessment of th e urinary activity of proximal and distal tubule enzymes. Neutral-like endo peptidase (NEP-like) and angiotensin-converting enzyme (ACE) were the proxi mal tubule enzymes assessed, while prolyl-endopeptidase (PE) and serine-end opeptidase H1 and H2 were the distal tubule enzymes analyzed. Urine was col lected at diagnosis (T0) and after 2 (T2) and 6 (T6) months of follow-up. N EP-like enzyme activity (nmol/mg creatinine; median quartile range) was inc reased at diagnosis, and this remained stable during the first 6 months (T0 18.30+/-83.26, T2 17.32+/-49.56, T6 23.38+/-107.18). Urinary activity of t he other enzymes was as follows: ACE (mU/ml per mg creatinine) T0 0.08+/-0. 16, T2 0.06+/-0.10, T6 0.18+/-0.29; PE (nmol/mg creatinine) T0 6.70+/-84.87 , T2 9.55+/-69.00, T6 13.67+/-28.70; serine-endopeptidase H1 (nmol/mg creat inine) T0 7.86+/-26.95, T2 17.17+/-59.37, T6 18.19+/-79.14; and serine-thio l-endopeptidase H2 (nmol/mg creatinine) T0 3.06+/-21.97, T2 12.06+/-32.42, T6 16.22+/-44.06. Thirty other healthy children matched for age and gender were considered as a control group. This group was assessed once and the re sults were: NEP-like activity 6.05+/-10.54, ACE 0.11+/-0.22, PE 7.10+/-13.3 6, H1 5.00+/-17.30, and H2 6.00+/-20.16. In conclusion, we observed that NE P-like and HI enzymes exhibited significant increased urinary activity 6 mo nths after the diagnosis. This increase occurred in spite of the disappeara nce of clinical symptoms, which occurred 2 months after the diagnosis. We b elieve that the increase in urinary enzymatic activity could be a manifesta tion of a silent tubular dysfunction following an episode of acute post-inf ectious glomerulonephritis.