People experiencing brain bleeds exhibited almost seven times higher blood levels of a specific protein known as glial fibrillary acidic protein (GFAP) compared to those who suffered from strokes due to clots, as revealed by a study in Germany.
According to an initial study that will be presented at the American Stroke Association’s International Stroke Conference 2025, a blood test could quickly differentiate between brain bleeds and strokes caused by clots even before individuals with stroke symptoms arrive at the emergency department. This conference will take place in Los Angeles from February 5-7, 2025, and is a premier venue for researchers and clinicians focused on stroke and brain health.
The longer it takes to diagnose and treat a stroke, the greater the damage to brain tissue and the worse the potential outcomes for the patient. It is essential to identify whether a stroke is hemorrhagic (caused by bleeding) or ischemic (caused by a clot) before starting any treatment. Typically, this differentiation is made using imaging techniques, which can take several hours while patients are stabilized and transported for scanning, during which critical brain cells may perish.
“It’s vital to distinguish between these stroke types, as they require completely different treatments. Ischemic strokes need clot-busting drugs or removal of the clot, while bleeding strokes require measures to lower blood pressure and medications to counteract certain blood thinners,” explained Love-Preet Kalra, M.D., the lead author and a neurology resident at RKH Hospital Klinikum Ludwigsburg, Germany.
The research team examined whether measuring GFAP levels in the blood could help in promptly identifying different types of strokes. GFAP is a protein found in the brain and is released into the bloodstream when brain cells are harmed. Its measurement is already utilized in assessing traumatic brain injuries.
In a related study published in 2024, Kalra and associates discovered that GFAP levels could quickly identify patients with bleeding strokes among those who were unresponsive. This study aimed to see if GFAP levels could differentiate between hemorrhagic and ischemic strokes, as well as conditions that resemble a stroke. Blood samples were collected by emergency medical services before patients arrived at the hospital for analysis.
The findings indicated that GFAP levels were:
- nearly seven times higher in individuals with bleeding strokes compared to those with clot-induced strokes (208 picograms per milliliter, or pg/mL, versus 30 pg/mL);
- over four times higher in patients experiencing bleeding strokes than those with stroke mimics (208 pg/mL compared to 48 pg/mL);
- able to rule out a bleeding stroke if levels were below 30 pg/mL in patients suffering from moderate to severe neurological deficits;
- capable of accurately predicting bleeding strokes with 90%-95% certainty when age-based thresholds were applied. These age categories were evenly spread across below 72, between 72 and 83, and above 83, with the lower age cut-off being very low.
- elevated in bleeding stroke patients who were on blood-thinning medications compared to those not on such drugs.
“I was genuinely surprised by the remarkably high GFAP values seen in patients with bleeding strokes who were on blood thinners. Additionally, in cases with moderate or severe deficits, we could exclude bleeding strokes based solely on GFAP levels below 30 pg/mL,” Kalra remarked.
If these results are validated through larger studies, Kalra believes that early measurements of GFAP could revolutionize the treatment approach for individuals exhibiting stroke symptoms.
“Initiating treatments to reduce blood pressure and counteract blood thinners could be performed before reaching the hospital, significantly impacting clinical practice. In the future, treatments for both blood thinning and clot busting might even begin in the prehospital setting,” Kalra said.
One limitation of this test is that it requires a centrifugation process (which separates blood components). Additionally, GFAP levels can increase with age, leading to ambiguity where mild bleeding strokes might not be recognized or could be incorrectly interpreted as ischemic strokes in older patients.
“This study highlights that GFAP levels, an indicator of brain injury, are significantly higher in patients with brain hemorrhages compared to those with clot-caused strokes. This suggests that GFAP could be a valuable prehospital tool for evaluating brain injuries. However, the study was relatively small, and to be effective, both blood samples and the GFAP test need to be accessible at the point of care in the field. Currently, most ambulances and emergency services lack the capability to perform this blood test,” stated Louise D. McCullough, M.D., Ph.D., FAHA, an expert from the American Heart Association who was not involved in the study.
Details about the study’s background or design include:
- The study involved 353 individuals (average age 75, 47% women) who reached the emergency room within six hours of stroke symptom onset.
- Participants with history of brain tumors or who had experienced strokes or severe brain injuries in the last three months were excluded from the analysis.
- Blood samples were collected before patients arrived at RKH Hospital Ludwigsburg, Germany, where GFAP levels were tested utilizing a portable blood analyzer.
- Brain imaging confirmed intracerebral hemorrhage (bleeding stroke) in 76 participants, clot-induced strokes in 258, and conditions that mimicked strokes (such as seizures or migraines) in 19.
- GFAP levels were contrasted among the groups based on their diagnoses upon hospital discharge.
