Urinary N-acetyl-beta-D-glucosaminidase excretion in term and preterm neonates

Urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion was measured in term and preterm neonates on days 1, 4, 7, 14 and 28 of life. Urinary NAG showed a peak level on day 4 or 7 in these infants. In addition, it tended to be higher with the degree of prematurity. In sick preterms who were depressed at birth and had respiratory failure, the NAG activity was further elevated during the first 2 weeks, suggesting the presence of renal tubular injury in this period. These observations thus suggest that urinary NAG may be a sensitive measure of renal maturation or damage in neonates.