The Serum S100B Concentration Is Age Dependent

S100B is a 21-kDa calcium-binding protein produced and released primarily by astrocytes in the central nervous system (CNS), where it exerts neurotropic and gliotropic actions (1). Several studies have investigated the potential role of S100B as a peripheral biochemical marker of neural injury, including reactive gliosis, astrocytic death, and/or blood-brain barrier dysfunction (2). Increased cerebrospinal fluid (CSF) and/or serum S100B has been reported in several acute and chronic injuries, including traumatic brain injury (3), stroke (4), Alzheimer disease (5), schizophrenia (6), HTLV-I-associated myelopathy (7), and systemic lupus erythematosus (8). Previous neurodevelopmental studies have demonstrated age-related changes in S100B tissue expression and distribution in the CNS in mammals, which may be related to the different roles of this protein in distinct brain regions during the fetal period, adulthood, and aging (1)(9). Furthermore, S100B concentrations in CSF have been noted to increase with age in healthy individuals (10). Because these increases are more evident in men than women (11), S100B concentrations in CSF may be sex and age dependent, suggesting that age- and sex-matched controls may be necessary for studies of S100B in CSF. To determine the usual concentrations for plasma S100B in adults, Wiesmann et al. (12) measured the protein in healthy blood donors and found no differences with sex and age in individuals 18–65 years of age, in agreement with our findings in previous studies in adults (6)(7)(8). To our knowledge, however, S100B concentrations in blood in childhood and adolescence were not established until recently. The present study was performed to verify S100B serum concentrations in healthy individuals of different ages, ranging from neonates to adults. We collected blood samples from 19 healthy term neonates (<48 h of age) and from 25 healthy children 4–16 years of age undergoing routine clinical and …