Urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) as early markers of renal tubular dysfunction in sick neonates

Abstract

Urinary beta 2-microglobulin, creatinine, N-acetyl-beta-D-glucosaminidase (NAG), sodium, potassium and plasma beta 2-microglobulin, and creatinine were measured in 34 healthy neonates (including 15 term, 12 prematures with a birth weight between 1.5 and 2.5 kg, 7 prematures with a birth weight less than 1.5 kg), 29 sick neonates (including 6 term, 10 prematures with a birth weight between 1.5 and 2.5 kg, 13 prematures with a birth weight less than 1.5 kg), and 13 term neonates born with meconium-stained amniotic fluid at 1, 3, and 5 days of age. Our data revealed that urinary beta 2-microglobulin, NAG, NAG index (NAG/creatinine), and the sodium concentration were significantly higher in sick preterm and term neonates than in healthy neonates (p less than 0.05). Urinary concentrations of beta 2-microglobulin and NAG were also higher in neonates born with meconium-stained amniotic fluid than in healthy neonates. We conclude that sick neonates have a higher incidence of acute tubular injury. The elevated levels of urinary beta 2-microglobulin and NAG in neonates born with meconium-stained amniotic fluid indicate the existence of tubular dysfunction, probably due to perinatal distress.