Point of Care UCHL1/GFAP for Rapid Assessment of Undifferentiated Trauma Patients

BACKGROUND: Rapid discrimination of traumatic brain injury (TBI) from hemorrhagic shock remains challenging during initial trauma evaluation. Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) and glial fibrillary acidic protein (GFAP) are established TBI biomarkers; however, UCHL1 may also increase in systemic shock. We evaluated a point-of-care whole-blood UCHL1/GFAP assay in undifferentiated severe injury and examined associations with TBI, massive transfusion, and in-hospital mortality. STUDY DESIGN: In this prospective, single-center study, 273 consecutive highest-level trauma activations at risk for TBI or hemorrhage were enrolled between February 2025 and March 2026. UCHL1 and GFAP were measured using the iSTAT-Alinity platform and compared with arrival point-of-care lactate. Associations were assessed using Mann-Whitney U testing, receiver operating characteristic analysis, Fisher's exact testing, and logistic regression. RESULTS: GFAP >218 pg/mL (OR 73.2, p<0.001) and UCHL1 >2003 pg/mL (OR 3.3, p<0.001) were associated with TBI, whereas lactate >1.8 mmol/L was not (OR 0.6, p=0.12). Massive transfusion was associated with UCHL1 >2678 pg/mL (OR 3.9, p=0.002) and lactate >4 mmol/L (OR 5.5, p<0.001). In-hospital mortality was associated with GFAP >1532 pg/mL (OR 14.4, p<0.001), UCHL1 >2866 pg/mL (OR 4.1, p<0.001), and lactate >5.8 mmol/L (OR 2.0, p=0.03). Extreme GFAP elevation (>10,000 pg/mL) was strongly associated with mortality (30/34 patients; OR 35.4; PPV 88.2%; p<0.001). CONCLUSIONS: Point-of-care UCHL1/GFAP functions as a global trauma biomarker. Concurrent elevation of GFAP and UCHL1 is strongly associated with TBI, whereas isolated UCHL1 elevation may reflect hemorrhagic shock. Extreme GFAP elevation identifies patients at exceptionally high risk for in-hospital mortality, even without radiographic stratification.Level of Evidence: Level II.