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Glial Fibrillary Acidic Protein (GFAP) in Serum by Line Blot Immunoassay

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

This test measures the level of GFAP, a protein found in certain brain cells called glial cells. It helps identify conditions that may affect the brain or spinal cord.

Quick summary

GFAP testing may assist in diagnosing neurological conditions like brain tumors or swelling (edema).

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

Key facts at a glance

LOINC
83001-8
Short code
Glial nuc type 1 IgG SerPl Ql Line blot
Synonyms
Glial nuc type 1 IgG SerPl Ql Line blot
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
CPT
82784
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 severe headaches, confusion, weakness, or neurological issues that suggest a brain-related problem. It could also be used to monitor conditions like brain tumors, stroke recovery, or other neurological disorders.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw at your doctor’s office or lab. If you’re on blood thinners, let your doctor know before the test.

What the Test Results Mean

Higher than expected GFAP levels may indicate brain injury, swelling, or certain brain diseases. Lower levels may be normal or could relate to other health factors. Your doctor will interpret results in the context of your symptoms and medical history.

Common Conditions Monitored

This test is often used to diagnose or monitor conditions like brain tumors (such as gliomas), subarachnoid hemorrhage, encephalitis, or other neurological disorders affecting glial cells.

Frequently asked questions

What causes elevated GFAP levels?
Elevated GFAP levels can result from brain trauma, stroke, brain tumors, or inflammatory diseases like encephalitis. It may also appear in conditions causing brain swelling or other neurological damage.
How is this test different from other brain-related tests?
Unlike standard imaging (like MRI), this test measures a protein specific to glial cells. It provides additional information when symptoms suggest brain involvement but imaging alone isn’t conclusive.
Can diet or medications affect GFAP levels?
Dietary factors or common medications typically do not affect GFAP levels. However, if you’re on blood thinners, inform your doctor before testing to ensure safe blood collection.
  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