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HelpTest Code Billings Clinic: 1254 Mayo: GD65C Glutamic Acid Decarboxylase (GAD65) Antibody Assay, Spinal Fluid
Reporting Name
GAD65 Ab Assay, CSFPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Possible use in evaluating patients with autoimmune encephalitis, stiff-person syndrome, autoimmune ataxia, autoimmune epilepsy, and other acquired central nervous system disorders affecting gabaminergic neurotransmission
Method Name
Radioimmunoassay (RIA)
Ordering Guidance
This test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. The specific waiting period before specimen collection will depend on the isotope administered, the dose given, and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive specimens received in the laboratory will be held one week and assayed if sufficiently decayed or canceled if radioactivity remains.
Specimen Required
Container/Tube: Sterile vial
Specimen Volume: 1.5 mL
Collection Instructions: Submit specimen from collection vial 2.
Specimen Type
CSFSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
≤0.02 nmol/L
Reference values apply to all ages.
Interpretation
Intrathecal synthesis of glutamic acid decarboxylase 65 (GAD65) antibody has been demonstrated in patients with stiff-man syndrome, but cerebrospinal fluid (CSF) values are log orders lower than serum. We have not determined the frequency of GAD65 antibodies in CSF of patients with various diagnoses.
Day(s) Performed
Monday through Sunday
Report Available
3 to 6 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86341
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| GD65C | GAD65 Ab Assay, CSF | 94359-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 21702 | GAD65 Ab Assay, CSF | 94359-7 |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.