The gold standard for diagnosing a concussion is a CT scan of the head. But what if you don't have a concussion? That would be unnecessary radiation, except now you have another option: a blood test.

Yes, a blood test now looks for biomarkers for concussion. That means a subset of the world's twenty million people who get CTs because they're not sure whether they have a concussion won't have to.

Several European countries use a test that looks for a molecule called S-one hundred-B, but the correlation between elevated levels of this molecule and positive CT scans aren't as strong and so it is not approved for use in the US. However, the FDA did approve two other proteins that can serve as biomarkers for concussion and they are Ubiquitin C-terminal hydrolase-L-one or UCH-L-one and glial fibrillary acidic protein or GFAP.

This discovery was the result of a test of two thousand participants who sustained a traumatic brain injury and received a CT scan within twelve hours. Their blood was tested for levels of the two proteins. If those with elevated levels corresponded with positive CT scans, then these biomarkers would be accurate indicators for brain injury.

The results of this largest ever study of brain injury biomarkers showed that all patients who had positive CT scans also had significantly elevated levels of both UCH-L-one and GFAP. The blood marker test accurately predicted the presence of a traumatic brain injury ninety-five percent of the time. The FDA approved the test in February two thousand eighteen, so now doctors don't have to order unwarranted CT scans which spares many people from a high lifetime radiation exposure.