title: Effects of head and extracranial injuries on serum protein S100B levels in trauma patients.
abstract: BACKGROUND
  Serum protein S100B determinations have been recently suggested as markers of traumatic brain injury. However, little is known about the effects of extracranial injuries on S100B levels in trauma patients.
  
  
  METHODS
  We studied 224 patients with head trauma (54 of whom also had extracranial injuries), 155 patients with various types of extracranial injuries, and 8 healthy pilots exposed to high Gz forces. The head trauma patients had either no brain injury (n = 35), mild brain injury (n = 165), or moderate to severe brain injury (n = 24). The extracranial injuries were divided into small and large injuries. Serum protein S100B levels were determined from samples taken within 6 hours after the trauma event.
  
  
  RESULTS
  The head trauma patients had a significantly higher median S100B (0.17 microg/L) than the patients with extracranial injuries (0.07 microg/L) (p < 0.001). Serum S100B levels also correlated with the severity of brain injury (p < 0.001), the highest values occurring in the patients with moderate to severe brain injury (1.27 microg/L). However, large extracranial injuries also elevated S100B levels (0.35 microg/L), whereas small extracranial injuries in the absence of head trauma did not significantly affect S100B levels (0.07 microg/L). Above the cutoff level of 0.13 microg/L, there were 61% of the head trauma patients and 26% of those with extracranial injuries (Pearson chi test, p < 0.001). However, only 4% of the patients with purely extracranial injuries had a concentration of S100B above the cutoff level of 0.50 microg/L, whereas the head trauma patients with moderate to severe brain injury exceeded this cutoff in 67% of the cases. Exposure to high Gz forces did not influence serum S100B levels in healthy individuals.
  
  
  CONCLUSIONS
  We conclude that serum S100B is a sensitive marker of brain injury, which correlates with the severity of the injury. Large extracranial injuries also elevate S100B levels. However, S100B has a high negative predictive power, and the finding of a normal S100B value shortly after trauma should thus exclude significant brain injury with a high accuracy.
authors.affiliation: Department of Neurology, Oulu University Hospital, Oulu, Finland. osavola@paju.oulu.fi
authors.forename: Olli
authors.initials: O
authors.lastname: Savola
authors.forename: Juhani
authors.initials: J
authors.lastname: Pyhtinen
authors.forename: Tuomo K
authors.initials: TK
authors.lastname: Leino
authors.forename: Simo
authors.initials: S
authors.lastname: Siitonen
authors.forename: Onni
authors.initials: O
authors.lastname: Niemelä
authors.forename: Matti
authors.initials: M
authors.lastname: Hillbom
mesh_terms: D000007:Abdominal Injuries / Q000097:blood; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001930:Brain Injuries / Q000097:blood; D006259:Craniocerebral Trauma / Q000097:blood*; D005260:Female; D050723:Fractures, Bone / Q000097:blood; D006801:Humans; D008297:Male; D009414:Nerve Growth Factors / Q000097:blood*; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000097:blood*; D012680:Sensitivity and Specificity; D017695:Soft Tissue Injuries / Q000097:blood; D013180:Sprains and Strains / Q000097:blood; D014947:Wounds and Injuries / Q000097:blood*
chemical_list: D015415:Biomarkers; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579160:S100B protein, human