Glial Fibrillary Acidic Protein (GFAP) in Serum/Plasma by Immunoassay (Screening)
This test measures a protein produced by certain supportive brain cells called astrocytes, which can help detect brain injuries or diseases affecting these cells.
["GFAP levels may rise after brain trauma or certain neurological conditions."]
Key facts at a glance
- LOINC
- 94341-5
- Short code
- Glial nuc type 1 IgG Titr Ser IF
- Synonyms
- Glial nuc type 1 IgG Titr Ser IF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 8
- Ref high
- 61
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- if
- CPT
- 82977
- SNOMED
- 3110003
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your doctor may recommend this test if you’ve experienced a head injury, symptoms like headaches, confusion, or neurological issues, or if you have a suspected condition like brain tumors, stroke, or neurodegenerative diseases. It’s often used as part of a screening process to identify potential brain abnormalities.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. If you’re on blood thinners, let your doctor know before the test.
What the Results Mean
Elevated GFAP levels may suggest damage or disease affecting astrocytes, but results alone aren’t diagnostic. Your doctor will review them alongside your symptoms and other tests.
Common Conditions Monitored
This test helps monitor conditions like traumatic brain injury, subarachnoid hemorrhage, brain tumors, multiple sclerosis, or other neurodegenerative disorders where astrocytes play a role.
Reference range
Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
GFAP is a marker for astrocyte activation, which can occur in response to brain trauma, inflammation, or disease. While not specific to any single condition, it’s useful for detecting widespread brain injury or certain neurological pathologies that require further investigation.
Short name
GFAP Screen
Frequently asked questions
What does a high GFAP level indicate?
How soon will I get my results?
Can I take anything before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy