Emergency department measurement of urinary S100B in children following head injury: can extracranial injury confound findings?

Objective: To assess the potential role of urinary S100B as a prognostic biochemical marker following head injury in children in a UK emergency department setting. Methods: A case-control pilot study was performed in 20 patients with head injury and 15 controls (with extracranial trauma) aged <13 years and within 12 h of their injury recruited over a 4-month period. Urinary S100B levels were measured at presentation to the emergency department. Results: The two groups showed no significant differences in basic characteristics (height, weight, time to sample collection). 50% of the case group had measurable concentrations of S100B following head injury (range 0.02–0.07 µg/l). All patients in the control group had measurable S100B concentrations following extracranial trauma (range 0.02–0.09 µg/l). No significant rise in S100B concentrations occurred in two patients with severe head injuries (Glasgow Coma Score (GCS) <9) and in one patient with a moderate head injury (GCS 10), despite significant injuries on the CT scan. Conclusion: Despite detecting measurable S100B levels in urine following head injury, the same levels are measured following extracranial trauma. Urinary S100B is therefore not useful as an early biochemical marker following head injury in children.