Sustained release of neuron-specific enolase to serum in amateur boxers.

We assess the potential of a panel of serum biomarkers to identify chronic neuronal injury in amateur boxers as compared to healthy controls without any history of head trauma. Observational case-control study. A panel of serum biomarkers was measured by a novel biochip array technique on the Evidence Investigator. Serum samples were taken after a 2-month period of nonparticipation in boxing. Boxers had higher serum levels of neuron-specific enolase (NSE, median [range] 11 [2.3-41] ng/mL) than controls (4.8 [0.78-27] ng/mL, p = 0.014) but unchanged levels of the other brain damage biomarker candidates, S-100B, brain-derived neurotrophic factor and heart-type fatty acid binding protein. The more than doubled median serum level of NSE in boxers after an extended resting period suggests that repetitive head trauma results in sustained release of this brain-specific protein to the peripheral circulation.