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GAD65 Ab assay, CSF

Lab Section:  Sendout  
Lab Location:  Sendout
Reference Lab: Mayo 
Test ID: LAB6686 
Methodology: Immunoprecipitation Assay
Schedule: Mon-Fri
Reported: 7 days
Specimen Requirements:  Collection: 3.0 mL Cerebrospinal Fluid in a Sterile Container.
Pediatric volume: 1 mL.
Unacceptable conditions: Grossly lipemic, iceteric, and hemolytic specimens
Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours


Clinical Indications: Glutamic acid decarboxylase (GAD) is a neuronal enzyme involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA). Serum antibodies directed against the 65-kd isoform of GAD (GAD65) are detected in heightened frequency in a variety of autoimmune neurologic disorders, including stiff-man (Moersch-Woltman) syndrome, autoimmune cerebellitis, some idiopathically acquired epilepsies, some rare acquired encephalomyelopathies with and without neoplasia, and in myasthenia gravis and Lambert-Eaton myasthenic syndrome. GAD65 antibodies account for the majority of clinically recognized pancreatic islet cell antibodies, and are an important serological marker of predisposition to type 1 (insulin-dependent) diabetes. GAD65 autoantibodies also serve as a marker of predisposition to autoimmune disorders that commonly or sometimes coexist with type 1 diabetes, including autoimmune thyroid disease (eg, thyrotoxicosis, Graves disease, Hashimoto thyroiditis, hypothyroidism), pernicious anemia, premature ovarian failure, Addison disease (idiopathic adrenocortical failure), and vitiligo. GAD65 antibodies are found in the serum of approximately 8% of healthy subjects older than age 50, usually in low titer, but often accompanied by related "thyrogastric" autoantibodies.

Reference Interval:  See patient report or consult reference laboratory website.
CPT Code(s): 86341
Last Changed: 11/09/2016 14:44:56
Last Reviewed: 12/26/2016 23:45:38