Diagnostic and Prognostic Value of Serum Glial Fibrillary Acidic Protein in Acute Ischemic Stroke

<b>Background:</b> Acute ischemic stroke (AIS) remains a major cause of morbidity and mortality, with an unmet need for reliable blood-based biomarkers. Glial fibrillary acidic protein (GFAP), an astrocytic structural protein, is established in hemorrhagic stroke and traumatic brain injury, but its role in AIS remains incompletely defined. <b>Methods:</b> In this retrospective case-control study, we enrolled AIS patients and healthy controls. Serum GFAP was measured within 24 h using the Lumipulse G1200 automated assay. Stroke severity and outcome were assessed with the National Institutes of Health Stroke Scale (NIHSS) and functional outcome with the modified Rankin Scale (mRS). Associations with clinical measures were explored using Spearman correlation, and diagnostic accuracy was determined by ROC analysis. <b>Results:</b> GFAP levels were significantly higher in AIS patients than controls (median 132.9 vs. 30.0 pg/mL, <i>p</i> < 0.001). The ROC analysis yielded an AUC of 0.88 (95% CI 0.81-0.96). A cutoff of 71 pg/mL achieved 74% sensitivity and 92% specificity, while 150 pg/mL and 32 pg/mL optimized positive and negative predictive values (95% and 96%). GFAP was correlated with stroke severity (NIHSS, ρ = 0.37-0.40, <i>p</i> < 0.001) and disability (mRS, ρ = 0.48-0.49, <i>p</i> < 0.001). No significant differences appeared across TOAST subtypes. <b>Conclusions:</b> Serum GFAP is significantly elevated in AIS and demonstrates strong diagnostic and prognostic value. Integration of GFAP into clinical workflows may enhance early stroke detection and outcome prediction, supporting its role as a promising biomarker in AIS.