Glutamic Acid Decarboxylase-65 Antibody

Test Code

GAD-65

Quest Code

34878

Alias/See Also

GAD-65
GAD
Glutamic Acid Decarboxylase Auto Ab

CPT Codes
86341

Preferred Specimen

0.2 mL serum

Minimum Volume

0.1 mL

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 14 days
Frozen: 60 days

Methodology
Enzyme Linked Immunosorbent Assay (ELISA)

Setup Schedule

Set up: Sun-Fri; Report available: 3-5 days

Limitations

GAD-65 antibodies are detected in 20% of diabetic twins who remain disease-free for long periods of time and in 8% of healthy individuals.

Reference Range

<5 IU/mL

Clinical Significance

Glutamic acid decarboxylase (GAD-65) antibody is useful to diagnose insulin dependent diabetes mellitus [Type I diabetes (autoimmune-mediated diabetes)] to assess risk for development of Type I diabetes, to predict onset of Type I diabetes, and risk of development of related endocrine disorders, e.g., thyroiditis. Before clinical onset, Type I diabetes is characterized by lymphocytic infiltration of the islet cells, and by circulating autoantibodies against a variety of islet cell antigens, including GAD-65, IA-2 (a tyrosine phosphatase-like protein), and insulin (IAA).

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Last Updated: September 17, 2019

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.