Type of test Blood

Normal findings

 UCH-L1 ≤ 327 pg/mL ,, GFAP ≤ 22 pg/mL

Test explanation and related physiology

Traumatic brain injury (TBI) caused by external physical force disrupts normal brain function and can result in temporary or permanent coma. Impairment of cognitive abilities or physical functioning can also occur. When TBI is suspected, a neuro logical assessment using the 15-point Glasgow Coma Scale, a thorough neurological examination, and commonly a computed tomography (CT) scan of the head are done. CT scans are not only costly but are also a source of radiation exposure. Because 90% of patients with mild TBI (concussion) have a negative CT scan, use of a blood test for determining the possibility of serious TBI could be helpful in the emergency room setting.

BTI is a semiquantitative immunochemical chemiluminescent measurement of serum levels of UCH-L1 and GFAP. UCH-L1 is abundantly present in all neurons and accounts for 1%-2% of total brain protein. GFAP is expressed in astrocytes and is involved in many important central nervous system processes, including cell communication and the functioning of the blood–brain barrier. These proteins are released from the brain into the bloodstream and can be measured within 12 hours of TBI.

Nearly all patients with TBI noted on CT scan of the head will have an elevated level of either protein. Less than 1% of patients with normal levels of both proteins will have a positive CT scan of the head. In this group of individuals, a CT scan of the head may not be needed.

 Interfering factors

 • Levels of proteins vary with age. The test is considered accurate only for individuals that are over 18 years of age.

Procedure and patient care

 • See inside front cover for Routine Blood Testing.

 • Fasting: No

• Blood tube commonly used: Gold