Urinary N-acetyl- β -D glucosaminidase activity in newborns as a marker of hypoxic-ischemic tubular damage

Abstract

The cells of the proximal tubular epithelium, being of high metabolic activity, are very susceptible to hypoxia. N-acetyl-β-D-Glucosaminidase is an enzyme found especially in the proximal tubular epithelium. The place of routine laboratory tests and clinical evaluation in determining renal injury due to asphyxia in the newborn arc limited. Demonstration of hypoxicischemic tubular damage in its early stages in neonates by showing elevated levels of urinary N- acetyl- β- DGlucosaminidase (NAG). This study was conducted with the aim of demonstrating the practical applicability of urinary NAG level determination in the early diagnosis and monitoring of the renal injury due to hypoxia. In this study, the ratio of NAG/creatinine in the urine samples were compared between 19 asphyxiated and 16 healthy infants whose gestational and postnatal age and gender were matched. Urinary NAG/Cr ratios were significantly higher in the asphyxiated newborn on the days 1, 4, 7, and 14. It returned to normal at the 28th day. In addition, there were found to be a negative correlation between the Apgar scores and urinary NAG indices. Regular monitoring of the urinary NAG activity in the asphyxiated newborns appears to be a non-invasive and reliable laboratory finding that can demonstrate hypoxic renal injury in the early stages.