Background: Hypoxic-ischemic encephalopathy (HIE), an important disease in the asphyxiated newborn infants, usually leads to neonatal death and neurological sequelae. There have been no reliable and convenient methods for early identification of HIE. This study was undertaken to investigate the value of urinary S100B protein and lactate/creatinine (L/C) ratio in early diagnosis of neonatal hypoxic-ischemic encephalopathy.

Methods: Urinary S100B protein levels and L/C ratio were detected in 58 full-term newborns with HIE on the first, second and third day after birth, and the degree of HIE was assessed within the first seven days after birth. Twenty-five normal full-term neonates were enrolled as controls.

Results: The urinary S100B protein levels within the first three days and the L/C ratio on the first day after birth were significantly higher in newborns with HIE than in the controls (P<0.01). There was a positive correlation between urinary S100B protein level on the third day after birth and the L/C ratio on the first day after birth. The two indexes were positively correlated with the clinical grades of HIE (P<0.01). When the S100B protein level was 0.47 µg/L and the urinary L/C ratio was 0.55, their sensitivity and specificity in detecting urinary S100B protein alone on the third day after the birth was 90.4% and 91.9%, respectively. On the first day after birth, the L/C ratio showed the highest sensitivity (91.5%) and specificity (90.3%) in predicting HIE. Detecting the S100B protein level on the third day after birth and the ratio of L/C at the same time on the first day after birth significantly improved the accuracy in HIE diagnosis, and the sensitivity and specificity under the combined use of the two methods were 98.8% and 97.4%, respectively, which were higher than those from the individual use of the two methods.

Conclusions: Based on the clinical manifestations of the asphyxiated full-term newborns, monitoring urinary S100B protein levels and L/C ratio in the first three days after birth is of practical value in improving the accuracy of early diagnosis and clinical grading of HIE.