GAD65 Antibody (Sendout)

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General Information

Lab Name
GAD65 Antibody Assay
Lab Code
RGAD65
Epic Name
(not orderable in Epic)
External Test Id
GD65S
Description

Useful For:

  • Assessing susceptibility to autoimmune (type 1, insulin-dependent) diabetes mellitus and related endocrine disorders (eg, thyroiditis and pernicious anemia)
  • Distinguishing between patients with type 1 and type 2 diabetes

Ordering Guidance: Although a high positive result (>250 IU/mL) could be consistent with stiff-person syndrome, such a result by this assay has been shown to be insufficiently specific for this diagnosis¹ and is not recommended. For a comprehensive evaluation of patients with suspected stiff-person syndrome (classical or focal forms, such as stiff-limb or stiff-trunk) and progressive encephalomyelitis with rigidity and myoclonus, consider ordering Stiff-Person Spectrum Disorders Evaluation, Serum (Sendout) [OLTG #1108].

Ordering Note: Non-orderable sendout battery included in the GAD65 Ab Assay (Sendout) [RGD65] package.

***Alert: Effective 10/13/26, this test is no longer available at Mayo as a standalone order. Samples will be forwarded to ARUP Laboratories for GAD65 Antibody (Sendout) [OLTG #1201] and results will be reported under Miscellaneous ARUP Frozen Test (Sendout) [RARUPZ] due to a change in methodology, units, and reference range. A new battery for the ARUP GAD65 Antibody test will be available on 12/01/2026.***

References
  1. McKeon et al. GAD65 Antibody ELISA with Extended Reportable Range: Validation and Guidance for Neurological Practice. Annals of Clinical and Translational Neurology, 2026; 0:1–10. https://doi.org/10.1002/acn3.70378
Synonyms
64K Antibody, Anti GAD Ab, Anti-Glutamic Acid Decarboxylase Ab, Ataxia, Beta Cell Antibody, GD65S, Islet Cell Antibody, Pancreatic Islet Cell Ab, Stiff person, Stiff-man syndrome, Stiffman Syndrome
Components

Interpretation

Method

Radioimmunoassay (RIA)

Reference Range
Units: nmol/L
Female Male Unknown
AgeRange AgeRange AgeRange
0-0-0.02 0-0-0.02 0-0-0.02

Effective date: 06/01/2023

References
  1. McKeon et al. GAD65 Antibody ELISA with Extended Reportable Range: Validation and Guidance for Neurological Practice. Annals of Clinical and Translational Neurology, 2026; 0:1–10. https://doi.org/10.1002/acn3.70378

Ordering & Collection

Specimen Type
Blood
Collection

3 mL blood in a RED top tube or GOLD SST

Quantity
Requested: 1 mL serum
Minimum: 0.5 mL serum

Processing

Receiving Instructions

Centrifuge sample and aliquot serum into a separate plastic vial. Freeze serum at -20°C.

    PSPS Temporary Workflow:

    • Add RARUPZ to the original accession unless the order is from an interfaced client; see GAD65 Antibody (Sendout) [OLTG #1201] for further details.
    • If RGD65 orders are received from interface clients, they must be re-logged manually using the appropriate non-interfaced client code.
    • Leave the RGAD65 pending (do not credit/cancel). CAST will resolve this order upon result receipt.
    Misc Sendout

    Performance

    Lab Department
    Sendouts Mayo Lab (RF)(MARF)
    Frequency
    Available STAT?
    No
    Performing Location(s)
    Sendout Mayo Clinic Laboratories
    800-533-1710

    200 First Street Southwest
    Rochester, MN 55901

    Billing & Coding

    CPT Codes
    86341
    LOINC
    30347-9
    Interfaced Order Code
    UOW1802
    Interfaced Result Code
    UOW1802
    Billing Comments

    Radioimmunoassay (RIA)