RESUMO
Measurements of serum and cerebrospinal fluid concentrations of S-100B protein has been used to detect brain distress, and in the perinatal period are correlated with brain maturation and are used to assess cerebral damage after perinatal asphyxia. As S-100B protein is eliminated by the kidneys, and because collecting urine is a simpler procedure than collecting cerebrospinal fluid or blood, especially in high-risk infants in whom anemia attributable to repeated blood sampling is common, we aimed to investigate the relation of urinary S-100B protein to the severity of hypoxic-ischemic encephalopathy [HIE] and to the neurological outcome in full-term newborns with HIE. Routine laboratory variables neurologic patterns, ultrasound imaging, and urine concentrations of S-100B protein were determined at first urination and at 24 hours after birth in 34 infants with perinatal asphyxia and in 25 control subjects. The concentrations of S-100B protein in urine were measured using an immunoluminometric assay. Neurological examination and Denver Developmental Screening Test [DDST] were performed at 12 months in the survivors. The results were correlated with the degree of HIE, and the presence or absence of neurologic abnormalities at age 12 months. Urinary levels of S-100 protein [micro g/L] were significantly higher in asphyxiated infants with favorable outcome [group I] [0.93 +/- 0.31 at 2 hours, and 1.05 +/- 0.30 at 24 hours] and in asphyxiated infants with adverse outcome [group II] [2.62 +/- 0.92 at 2 hours and 4.78 +/- 2.11 at 24 hours] compared to controls [0.18 +/- 0.04 at 2 hours and 0.24 +/- 0.08 at 24 hours, P=0.001 for all]. Also, these levels were significantly higher in asphyxiated infants with severe HIE than infants with moderate HIE, and those with no or mild HIE, with P <0.001 [at 2 hr] and P <0.003 [at 24 hr]. S-100 levels were negatively correlated with perinatal pH in the infants and associated with abnormal CTG at admission to the labor ward. For prediction of neonatal outcome measured as severe HIE, the sensitivity of S100 >0.32 micro g/L [at 2 hours] was 100%, and the specificity was 92.3%. At 24 hours, the sensitivity of S100 >0.58 micro g/L was 100%, and the specificity was 97.4%. For prediction, of adverse outcome at 12 months, the sensitivity of S100 >0.32 micro g/L [at 2 hours] was 100%, and the specificity was 92%. At 24 hours, the sensitivity of S100 >0.58 micro g/L was 100%, and the specificity was 97%. The use of S-100B as a pathologic marker in urine offers a tool to identify which asphyxiated infants are at risk of hypoxic-ischemic encephalopathy and its possible neurologic sequelae, and provide a new perspective for improving the monitoring and care of newborns