A new blood test could help emergency responders determine whether a stroke is caused by bleeding or a blood clot before a patient even reaches the hospital, according to a preliminary study set to be presented at the American Stroke Association’s International Stroke Conference 2025. The test measures glial fibrillary acidic protein (GFAP), a brain-specific protein released when brain cells are damaged.
If validated in more extensive studies, this rapid diagnostic tool could transform emergency stroke care, enabling faster, more accurate treatment and potentially improving patient outcomes.
The Importance of Rapid Stroke Diagnosis
When a person experiences a stroke, every second counts. Brain tissue begins to die quickly, and delays in treatment can lead to severe disability or death. However, treating a stroke requires knowing whether it is:
- A hemorrhagic stroke (caused by bleeding in the brain) requires lowering blood pressure and reversing blood thinners.
- An ischemic stroke (caused by a clot blocking blood flow) requires clot-busting drugs or mechanical clot removal.
CT scans or MRIs are needed to differentiate between these two types, but getting a patient from the ambulance to radiology can take hours. This new blood test could allow paramedics to begin life-saving treatments before the patient arrives at the hospital.
GFAP Blood Test Shows High Accuracy in Stroke Diagnosis
Researchers at RKH Hospital Klinikum Ludwigsburg in Germany studied 353 people (average age 75, 47% women) who arrived at the emergency room within six hours of stroke symptom onset. Emergency medical services (EMS) collected blood samples before hospital arrival, and GFAP levels were analyzed.
The study found that:
- GFAP levels were nearly 7 times higher in patients with hemorrhagic stroke (208 pg/mL) than in those with ischemic stroke (30 pg/mL).
- GFAP levels were more than 4 times higher in hemorrhagic stroke patients than in those with conditions that mimic stroke, such as seizures or migraines (208 pg/mL vs. 48 pg/mL).
- A GFAP level below 30 pg/mL ruled out hemorrhagic stroke in all moderate-to-severe stroke cases, helping to narrow down treatment options quickly.
- The test used age-based cutoff points to predict hemorrhagic stroke with 90%-95% accuracy.
- Patients on blood thinners had even higher GFAP levels, making it easier to detect life-threatening brain bleeds in these high-risk individuals.
Lead author Dr. Love-Preet Kalra, a neurology resident at RKH Hospital, was particularly surprised by the results.
“I was personally surprised by the extremely elevated GFAP values in blood thinner-associated bleeding stroke and the fact that, in moderately or severely affected acute stroke patients, bleeding stroke could be excluded in all cases with GFAP lower than 30 pg/mL,” Kalra said.
A Potential Game-Changer for Prehospital Stroke Care
GFAP blood testing could revolutionize stroke care if further research confirms these findings.
- Emergency responders could begin treatment immediately, improving survival rates and reducing disability.
- Blood pressure-lowering drugs and blood-thinner reversal medications could be given in the ambulance for patients with a hemorrhagic stroke.
- In the future, clot-busting drugs or mechanical clot removal could also be started before hospital arrival for ischemic stroke patients.
“Treatment to lower blood pressure and reverse blood-thinning medications could be performed in the prehospital setting, leading to a huge change in clinical practice,” Kalra said.
American Heart Association. “Blood test may detect stroke type before hospital arrival, allowing faster treatment.” ScienceDaily. ScienceDaily, 30 January 2025. <www.sciencedaily.com/releases/2025/01/250130161839.htm>
