The Simoa Human Neurology 4-Plex B assay (N4PB) measures four important neurology biomarkers in both cerebrospinalfluid (CSF) and blood. The four targets are neurofilament light (NF-L), total tau, glial fibrillary acidic protein (GFAP), and ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1). All four biomarkers have been studied as indicators of traumatic brain injury (TBI) severity. The Simoa Human Neurology 4-Plex A assay (N4PA) is also designed to measure the same 4 analytes. In samples from patients with severe TBI, levels of GFAP often saturate signal in the N4PA assay. N4PB has been developed to generate 10X lower signal for GFAP while retaining the ability to measure GFAP in most samples from healthy individuals. This modification results in better data yield from sample sets with high GFAP levels.