Age dependence of serum β-N-acetylhexosaminidase (NAG) activity

Abstract

AbstractSerum N-acetyl-β-D-glucosaminidase (NAG; EC 3.2.1.30) is a hexosaminidase and may be a predictor of vascular injury, e.g., in infant respiratory distress syndrome, pneumonia, broncho-pulmonary dysplasia and necrotizing enterocolitis. To estimate the new diagnostic prospects we have modified our urinary NAG assay. In this sensitive colorimetric micro-assay, VRA-GlcNAc was used as a substrate. In the present study the age dependence of serum NAG activity was investigated in newborn babies, infants (1–24 months), children (2–18 years) and adults (19–80 years). Serum NAG activity was found to be age-dependent; it is higher in early childhood (11–59 U/l) but decreases to a constant value at the age of 1–2 years. After the age of 2 years it is similar to adults' NAG (10–30 U/l). In pediatrics age-matched reference ranges must be taken into consideration.