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Glutamic Acid Decarboxylase (GAD65) Antibody, Serum (Screening)

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

This test checks for antibodies against GAD65, a protein linked to certain autoimmune conditions affecting the nervous system.

Quick summary

["GAD65 antibodies may help diagnose or monitor conditions like type 1 diabetes or autoimmune neurological disorders."]

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

Key facts at a glance

LOINC
90829-3
Short code
GAD65 Ab CSF Line blot-aCnc
Synonyms
GAD65 Ab CSF Line blot-aCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like unexplained fatigue, nerve-related issues, or a family history of autoimmune diseases. It’s often used as part of a broader evaluation for conditions like diabetes, neuropathy, or cerebellar ataxia.

What to Expect During the Test

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab for analysis. Results are typically available within 1–3 business days.

How the Results Are Interpreted

Results are qualitative (positive/negative) rather than numeric. A positive result suggests the presence of antibodies, which may warrant further testing or follow-up by a specialist.

What It Means to Have Positive/Negative Results

A positive result may indicate an autoimmune response, but it doesn’t confirm a diagnosis alone. Your doctor will consider symptoms, other test results, and medical history to guide next steps.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

GAD65 antibodies are strongly associated with autoimmune conditions such as type 1 diabetes, cerebellar ataxia, and other neurological disorders. They can help identify individuals at higher risk or guide treatment decisions, such as monitoring for complications or managing symptoms.

Short name

GAD65 Antibody Screen

Frequently asked questions

What does a positive result mean for my health?
A positive result suggests your immune system may be attacking GAD65, which could be linked to conditions like diabetes or neurological disorders. Your doctor will discuss next steps, which may include additional tests or referrals to a specialist.
Will I need to prepare for this test?
No special preparation is needed. You can eat and drink normally before the test, but avoid heavy meals right before drawing blood to reduce discomfort.
Can I get false-positive or false-negative results?
While rare, false results can occur due to lab errors or other factors. If your initial result is positive, your doctor may repeat the test or order additional tests to confirm findings.
  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