Elevation of serum S100 protein concentration as a marker of ischemic brain damage in extremely preterm infants

Background Periventricular leukomalacia (PVL) is serious ischemic brain damage that occurs in extreme preterm infants. It is traditionally diagnosed by cranial echography. The purpose of this study was to investigate the relationship between serum S100 calcium-binding protein B (S100B) concentrations and ischemic brain damage, and to find the cutoff value for the early identification of ischemic brain damage in high-risk preterm infants. Methods At the age of 3 days, 7 days, 14 days, and 21 days, and before discharge, 22 extremely premature infants (i.e., gestational age <33 weeks) underwent blood sampling to determine the S100B concentrations and cranial echography examinations. The severity of ischemic brain damage in echographic images was scored on a scale of 0–11, and was recorded as the brain echography index (BEI). If the last BEI value was ≥7, the enrolled infants were grouped in the brain damage group. Results Eight infants were assigned to the brain damage group and 14 infants were assigned to the no brain damage group. At each age point of the blood samplings, the serum S100B concentrations were significantly higher in the brain damage group than in the no brain damage group. There was a significantly positive correlation between the serum S100B concentrations and the BEI on the same day (r = 0.738, p < 0.001) and 7 days later (r = 0.774, p < 0.001). The receiver operating characteristic curve for the serum S100B concentrations showed that the area under curve was 0.985 (p < 0.001). The cutoff value of serum S100B of 1.0 μg/L had a sensitivity of 93.8% and specificity of 90.5% for the diagnosis of ischemic brain damage. Conclusion An elevation in the serum S100B concentration is highly associated with ischemic brain damage in extreme preterm infants. Ischemic brain damage in a high-risk preterm infant is strongly suggested if the early serum S100B concentration is > 1.0 μg/L.