GFAP and concussion: We extended the time limit for blood sampling from 6 h post-injury to 24 h post-injury because of the slower kinetics of GFAP compared to S100B in mTBI.21,36 Theoretically, the longer half-life of GFAP could make its use more efficient than S100B in the acute management of mTBI, allowing a longer measurement time window in EDs.