Urinary S-100B Concentrations in Term and Preterm Infants at Risk for Brain Damage

Abstract

Background: Elevated serum concentrations of S-100B, a 21-kDa protein expressed in astroglial cells, has been used to assess cerebral damage after head trauma, infection, ischemia, and perinatal asphyxia. Objective: As S-100B is eliminated by the kidneys, we investigated the feasibility of measuring S-100B in urine of newborns with severe perinatal asphyxia, and in very low birth weight (VLBW) preterm infants at risk for neurodevelopmental impairment. Methods: We first analyzed urine samples of 8 term or near-term newborns without major medical problems, followed by urine samples of 2 term newborns with severe birth asphyxia, and finally urine samples of 8 VLBW (gestational age 24–28 weeks) infants collected every 4 h for up to 10 days. Results: Urinary S-100B concentrations in 8 term or near-term newborns without major medical problems were consistently <1 µg/l. In 2 term newborns with severe asphyxia (Apgar 0/0/0 and 0/2/4) who subsequently had widespread cerebral damage on magnetic resonance imaging, peak urinary S-100B concentrations on the first day of life were 28.1 and 28.4 µg/l, respectively. In 5/8 VLBW infants, urinary S-100B was >1 µg/l in samples obtained on the first day of life (range 1.2–44.9 µg/l, median 6.8 µg/l). Peak S-100B in urine samples collected during the first 12 h of life were negatively related to gestational age (R_s = –0.882, p = 0.009). Three of the 8 preterm infants had peak urinary concentrations >10 µg/l but neither ultrasound signs of brain damage nor neurodevelopmental delay at 1 year corrected age. Conclusions: The determination of urinary S-100B concentrations might be helpful in term infants with severe asphyxia, while high urinary S-100B concentrations in preterm infants are to be attributed to immaturity.