A Biomarker for Brain Injury
Two proteins detectable by a simple blood test can help determine whether or not patients require CT scans following traumatic brain injuries
How do we diagnose traumatic brain injury (TBI)? Most people immediately think of patient-reported symptoms, functional neurological testing, or perhaps imaging to spot damage to our most delicate organ. It’s unlikely that your first thought was of a blood test – and yet that is precisely the approach approved earlier this year by the US Food and Drug Administration (FDA) and published recently in The Lancet Neurology.
Study author Robert Welch explains, “[Intracranial injury biomarkers] have been a topic of need and development for a long time. Ours was a clinical study that evaluated the new test against a gold standard (CT scan) for detecting traumatic intracranial injury.” The goal of the test is to reduce the use of CT scanning, which is costly, resource-intensive, and subjects patients to a dose of radiation equivalent to seven years of natural exposure – but, at the same time, to ensure that there is no increased risk of missing an injury.
The test detects two proteins, ubiquitin C-terminal hydrolase-L1 (UCH-L1) and glial fibrillary acidic protein (GFAP), both of which are naturally present in the brain – but significantly elevated after TBI. The test showed 97.6 percent sensitivity for the detection of intracranial injury, and 100 percent sensitivity for neurosurgically manageable lesions. However, it is not intended to replace CT scans entirely. “It will likely be a screening test that indicates a need for further diagnostic study – similar to D-dimer testing for suspected pulmonary embolism,” Welch explains. Patients whose UCH-L1 and GFAP levels indicate the possibility of TBI will continue to be referred for imaging; however, those in whom the test is negative can avoid a scan.
Welch also points out that the test is not intended to be a detailed resource offering continuous values. “Doctors need a yes/no result to make decisions on a patient’s need for further testing,” he says. “They want an objective test – and this fits the need.” But to be fully applicable in the clinic, Welch and his colleages would like to go one step further. Their ultimate goal? A rapid point-of-care platform so that the initial testing for TBI requires only minimal time and resources.
- JJ Bazarian et al., “Serum GFAP and UCH-L1 for prediction of absence of intracranial injuries on head CT (ALERT-TBI): a multicenter observational study”, Lancet Neurol, 17, 782–789 (2018). PMID: 30054151.