The primary objective of this study is to evaluate Ubiquitin C-terminal Hydrolase-L1 (UCH-L1) and Glial Fibrillary Acidic Protein (GFAP) biomarker levels in a population of CT-positive subjects (as determined by an independent Neuroimaging Review Committee) presenting acutely with traumatic brain injury (Glasgow Coma Scale score 9-15).

Inclusion Criteria:

• The Subject is at least 18 years of age at screening.
• The Subject has presented to a Health Care Facility (HCF) or Emergency Department (ED) with a suspected traumatically induced head injury, as a result of insult to the head from an external force.
• A Glasgow Coma Scale score of 9-15 at the time of Informed Consent.
• The subject is CT-positive for acute intracranial lesion(s) based on the local neuroradiologist's review of the subject's head CT scan.
• The CT scan and CT report used to determine eligibility must be available.
• The blood sample is collected as close to the time of head injury as possible, but no later than 12 hours.
• The Subject or their legal representative is willing to undergo the Informed Consent process prior to enrollment into this study

Exclusion Criteria:

• Participating in an interventional, therapeutic clinical study that may affect the results of this study (an observational study would be acceptable).
• Time of injury cannot be determined.
• Primary diagnosis of ischemic or hemorrhagic stroke.
• Venipuncture not feasible (i.e., skin integrity compromised at the venipuncture sites, blood vessel calcification (i.e., IV drug users, advanced atherosclerosis) both upper limbs missing (congenital or amputee)).
• The subject has a neurodegenerative disease or other neurological disorder including dementia, Parkinson's disease, multiple sclerosis, seizure disorder, or brain tumors.
• The subject has a history of neurosurgery within the last 30 days.
• Administration of blood transfusion after head injury and prior to the study blood draw.
• The subject is a female who is pregnant or lactating.
• The Subject is otherwise determined by the Investigator to be an unsuitable candidate for participation. If this criterion applies, a reason must be provided

Subjects eligible for study participation will be over the age of 18 with a standard of care head CT that has been confirmed to be CT-positive for acute intracranial lesions based on the local neuroradiologist's review and can undergo blood draw within 12 hours of head injury. Subjects who will be permitted into the study include those who will meet all the inclusion criteria and will have none of the exclusion criteria.