In recent years, the proteins glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) have emerged as promising biomarkers for mild TBI. Both proteins are known to become elevated after a head injury and are able to pass the blood-brain barrier.
To understand the behavior of these proteins over days after injury, a team of researchers took repeated blood samples from 584 patients who had been admitted to a trauma center (325 were diagnosed with a mild to moderate traumatic brain injury [MMTBI]; 259 had trauma without MMTBI) over one week. Computed tomography scans of the head were performed in 96.9% patients with MMTBI and in 37.5% trauma patients without MMTBI.
The researchers found that both GFAP and UCH-L1 were detectible within 1 hour of injury. GFAP reached a peak at 20 hours after injury and steadily decreased over 72 hours but was still detectable at 7 days. In contrast, UCH-L1 rose more rapidly after injury than GFAP, reached a peak at 8 hours, and decreased steadily over 48 hours.
When assessing if protein levels could distinguish trauma patients with and without MMTBI, GFAP proved quite predictive, ranging from 80-97% over the various time points (peaking at 97% between the 36-60 hour mark); UCH-L1 was not as accurate, peaking at 77%. GFAP also proved extremely accurate in predicting the patients with MMTBI who required a neurosurgical intervention (seven of the 325 underwent one), with accuracy ranges from 91-100%.
“In the context of developing a point-of-care test, the early and rapid rise of UCH-L1 could be used to detect TBI immediately at the scene of injury in settings such as in the ambulance, on the playing field, or at the battlefield. The longer half-life of GFAP makes it a favorable biomarker to use in both the acute and subacute phases of injury because it is able to detect CT lesions for up to 7 days after injury,” the authors wrote.
For related information, see the Psychiatric News article “Simple Method May Predict Recovery From Concussion.”