Remember how the FDA approved a blood test that could determine the severity of a concussion? It's now clear just why the FDA gave its approval. The Lancet Neurology has published the study at the heart of the decision, giving you a chance to verify the claims for yourself (if you're willing to pay, at least). As before, Banyan Biomarkers' test checks for the presence of two brain proteins (GFAP and UCH-L1) whose levels rise when there are signs of internal trauma. The FDA's claims check out -- out of 1,959 eligible test subjects, just three had CT scans turn up results when the blood tests were negative.