Glutamic Acid Decarboxylase (GAD65) Antibody Assay, Serum
Use
This test is used for assessing susceptibility to autoimmune (type 1, insulin-dependent) diabetes mellitus and related endocrine disorders such as thyroiditis and pernicious anemia. It aids in distinguishing between patients with type 1 and type 2 diabetes. Additionally, it helps confirm diagnoses of stiff-man syndrome, autoimmune encephalitis, autoimmune ataxia, brain stem encephalitis, autoimmune epilepsy, and autoimmune myelopathy. Antibodies against GAD65 are significant markers in these conditions and serve as important serological markers of predisposition to type 1 diabetes and related conditions.
Special Instructions
This test is preferably not requested for patients who have recently received radioisotopes due to potential assay interference. Specimens will be screened for radioactivity and held for one week or canceled if radioactivity persists. Red top tubes are preferred, but serum gel is acceptable for collection. Plastic vials should be used for specimen submission.
Limitations
Antibodies specific for glutamic acid decarboxylase (GAD65) account for most but not all antibodies detected in the islet cell antibody test. Testing in patients post-radioisotope administration may yield inaccurate results due to interference. Moreover, GAD65 antibodies, while a major marker, are complemented by other markers such as IA-2, insulin, and zinc transporter-8 antibodies. These nuances must be considered in the context of a comprehensive clinical evaluation.
New York Approved
Methodology
Immunoassay (RIA)
Biomarkers
LOINC Codes
- 30347-9
- 30347-9
Result Turnaround Time
3-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.5 mL
Minimum Volume
1 mL
Container
Red top or Serum gel; Plastic vial for submission
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis, Gross lipemia, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |