Glutamic Acid Decarboxylase-65, IA-2, and Insulin Autoantibodies (GAINAB)

Test Code

LAB2246

Quest Code

34878

Alias/See Also

GAINAB

CPT Codes
83519, 86337, 86341

Preferred Specimen

1 mL serum in gold top tube

Minimum Volume

0.5 mL

Other Acceptable Specimens

Plain red top tube

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

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

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Moderate to gross hemolysis or lipemia

Methodology
Enzyme Linked Immunosorbent Assay (ELISA)

Setup Schedule

AM Tuesday and thursday

Report Available

8 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-Chantilly VA

14225 Newbrook Drive

Chantilly, VA 20151-2228

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.