Urinary N-acetyl-β-D-glucosaminidase activity in healthy children

Aim: The principal aim was to establish paediatric reference data for the urinary N-acetyl-beta-D-glucosaminidase (U-NAG) activity. Method and Results: Two hundred and sixty-two healthy children aged 0-18 years (0-1 month, n = 38; 1 month-1 year, n = 50; 1-3 years, n = 50; 3-6 years, n = 46; 6-10 years, n = 29; 10-18 years, n = 49) had a urine sample collected and the U-NAG activity was evaluated by using fluorimetry and related to urinary creatinine as a nkat/mmol ratio. A strong age dependence of the U-NAG/creatinine ratio and its high interindividual variability in children was observed; the highest values of upper reference range being in the 0-1 month and 1 month-1 year groups (134.8 and 50, respectively), which dropped gradually to 7.25 in the oldest age group (10-18 years). Conclusion: The establishment of urinary NAG reference paediatric values is a potentially useful tool for the proper evaluation of renal tubular impairment in children.