IA2 Autoantibodies (Endocrine Sciences)

CPT: 86341
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Test Details

Synonyms

  • IA2 Antibodies
  • ICA512 Autoantibodies
  • Tyrosine Phosphatase Autoantibodies

Methodology

Immunoprecipitation assay

Additional Information

Type 1 diabetes, commonly referred to as insulin-dependent diabetes (IDDM), is caused by pancreatic beta-cell destruction that leads to an absolute insulin deficiency.1 The clinical onset of diabetes does not occur until 80% to 90% of these cells have been destroyed. Prior to clinical onset, type 1 diabetes is often characterized by circulating autoantibodies against a variety of islet cell antigens, including glutamic acid decarboxylase (GAD), tyrosine phosphatase (IA2), and insulin.2-7 The autoimmune destruction of the insulin-producing pancreatic beta cells is thought to be the primary cause of type 1 diabetes. The presence of these autoantibodies provides early evidence of autoimmune disease activity, and their measurement can be useful in assisting the physician with the prediction, diagnosis, and management of patients with diabetes. Autoantibodies to IA2, a tyrosine phosphatase-like protein, are found in 50% to 75% of type 1 diabetics at and prior to disease onset. These autoantibodies are generally more prevalent in younger onset patients. Because the risk of diabetes is increased with the presence of each additional autoantibody, the positive predictive value of the IA2 antibody test is enhanced when measured in conjunction with antibodies to GAD and insulin.

Specimen Requirements

Specimen

Serum, frozen

Volume

0.5 mL

Minimum Volume

0.1 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube or gel-barrier tube

Patient Preparation

No radioactive isotopes should be administered 24 hours prior to venipuncture.

Collection

Transfer the serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Storage Instructions

Freeze

Stability Requirements

Temperature

Period

Room temperature

3 days

Refrigerated

3 days

Frozen

107 days

Freeze/thaw cycles

Stable x6

Causes for Rejection

Radioactive isotopes administered 24 hours prior to venipuncture

Clinical Information

Footnotes

1. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care. 1997; 20(7):1183-1197. 9203460
2. Bonifacio E, Bingley PJ. Islet autoantibodies and their use in predicting insulin-dependent diabetes. Acta Diabetol. 1997 Oct; 34(3):185-193. 9401639
3. Verge CF, Gianani R, Kawasaki E, et al. Prediction of type I diabetes in first-degree relatives using a combination of insulin, GAD, and ICA512bdc/IA-2 autoantibodies. Diabetes. 1996 Jul; 45(7):926-933. 8666144
4. Bingley PJ, Bonifacio E, Williams AJ, Genovese S, Bottazzo GF, Gale EA. Prediction of IDDM in the general population: Strategies based on combinations of autoantibody markers.Diabetes 1997 Nov; 46(11):1701-1710. 9356015
5. Pietropaolo M, Hutton JC, Eisenbarth GS, et al. Protein tyrosine phosphatase-like proteins: Link with IDDM. Diabetes Care. 1997 Feb; 20(2):208-214. 9118776
6. Pietropaolo M, Peakman M, Pietropaolo SL, et al. Combined analysis of GAD65 and ICA512(IA02) autoantibodies in organ and nonorgan-specific autoimmune diseases confers high specificity for insulin-dependent diabetes mellitus. J Autoimmun. 1998 Feb; 11(1):1-10. 9480718
7. Borg H, Fernlund P, Sundkvist G, et al. Protein tyrosine phosphatase-like protein IA2-antibodies plus glutamic acid decarboxylase 65 antibodies (GADA) indicates autoimmunity as frequently as islet cell antibodies assay in children with recently diagnosed diabetes mellitus. Clin Chem. 1997 Dec; 43(12):2358-2363.9439455

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
141531 IA-2 Autoantibodies 141533 IA-2 Autoantibodies U/mL 31209-0
141531 IA-2 Autoantibodies 501016 IA-2 Autoantibodies N/A

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