Glutamic Acid Decarboxylase (GAD65) Antibody, Serum/Plasma (Qualitative)
This test measures whether your immune system produces antibodies against a protein called GAD65, which is linked to certain autoimmune conditions affecting the nervous system.
["This test helps diagnose or monitor autoimmune disorders that may affect nerve function."]
Key facts at a glance
- LOINC
- 13926-1
- Short code
- GAD65 Ab Ser-aCnc
- Synonyms
- GAD65 Ab Ser-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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
What Is This Test Measuring?
GAD65 is an enzyme found in nerve cells. Antibodies against GAD65 can indicate an autoimmune response, often seen in conditions like type 1 diabetes or certain forms of neurological disorders, such as stiff-person syndrome or limbic encephalitis. This test detects the presence of these antibodies in your blood.
Why Might You Need This Test?
Your healthcare provider may recommend this test if you have symptoms like unexplained nerve pain, muscle stiffness, unusual fatigue, or if you have a family history of autoimmune diseases. It may also be used to confirm a diagnosis in certain cases where other tests are inconclusive.
How Is the Test Performed?
A blood sample is drawn from a vein, usually in your arm. The sample is then tested in a lab to detect the presence of GAD65 antibodies. This test is qualitative, meaning it only tells you whether antibodies are present or not, rather than providing a specific quantity.
What Are Possible Results?
A positive result (antibodies detected) suggests an autoimmune response targeting GAD65. A negative result means no detectable antibodies were found. Results should always be interpreted by a healthcare provider in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Positive GAD65 antibody results are often associated with autoimmune conditions affecting the nervous system. For example, in type 1 diabetes, GAD65 antibodies may indicate early-stage autoimmune destruction of insulin-producing cells. In neurological disorders, these antibodies can be linked to inflammation or damage in nerve cells, potentially affecting movement, mood, or cognition. While this test is not definitive on its own, it can support a diagnosis or guide treatment decisions.
Short name
GAD65 Antibody (Qualitative)
Frequently asked questions
What Does a Positive or Negative Result Mean?
How Often Should I Get This Test?
Can This Test Be Done at Home?
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