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Glial Fibrillary Acidic Protein (GFAP) in Cerebrospinal Fluid (CSF) – Quantitative

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of GFAP, a protein produced by certain supportive cells in the brain and spinal cord, in your cerebrospinal fluid. It helps assess for conditions affecting the brain’s protective covering.

Quick summary

["GFAP CSF may help diagnose brain injuries or diseases affecting the brain’s protective layers."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
84927-3
Short code
Glial nuc type 1 Ab Ser Ql IF
Synonyms
Glial nuc type 1 Ab Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 have symptoms like sudden headaches, confusion, seizures, or neurological issues that could suggest bleeding, swelling, or damage to the brain’s protective layers. It’s also used in cases of suspected brain trauma, stroke, or certain brain tumors.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your back to collect a small amount of CSF through a procedure called a lumbar puncture (spinal tap). You may feel a brief pinch, but it’s usually not painful.

What the Test Results Mean

Elevated levels of GFAP in CSF may indicate conditions such as brain hemorrhage, brain tumors, or other brain injuries. Lower or normal levels do not rule out these conditions, so results are interpreted alongside clinical findings and other tests.

Common Conditions Monitored

This test is primarily used to diagnose or monitor conditions like traumatic brain injury, subarachnoid hemorrhage, brain tumors, or certain neurodegenerative diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

GFAP CSF

Frequently asked questions

What causes elevated GFAP levels in CSF?
Elevated GFAP levels can result from brain trauma (e.g., head injury), bleeding in the brain (e.g., subarachnoid hemorrhage), brain tumors, or other conditions causing inflammation or damage to the brain’s supportive tissues.
How soon will I get my results?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will discuss them with you during your follow-up visit.
Can I take anything before the test?
No, you should avoid any medications (including over-the-counter drugs) without consulting your doctor 24 hours before the test. Hydration is encouraged, but avoid caffeine or alcohol before the procedure.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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