Test Catalog

Test Id : IA2

Islet Antigen 2 (IA-2) Antibody, Serum

Useful For
Suggests clinical disorders or settings where the test may be helpful

Clinical distinction of type 1 from type 2 diabetes mellitus


Identification of individuals at risk of type 1 diabetes (including high-risk relatives of patients with diabetes)


Prediction of future need for insulin treatment in adult-onset diabetic patients

Method Name
A short description of the method used to perform the test

Radioimmunoassay (RIA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

IA-2 Ab, S

Lists additional common names for a test, as an aid in searching

Anti-IA2 Antibodies


Islet Cell Antibody

Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

Islet cell antigen 2 (IA2) testing is available individually (this test) and with glutamic acid decarboxylase 65-kilodalton isoform (GAD65), insulin, and zinc transporter 8 (ZnT8) antibodies as a part of DBS1 / Diabetes Mellitus Type 1 Evaluation, Serum. The evaluation is most appropriate to order in the following clinical contexts:

-Distinguishing type 1 (autoimmune) diabetes mellitus from type 2 diabetes mellitus

-Identifying individuals at risk of type 1 diabetes (including high-risk relatives of patients with diabetes) 

-Predicting future insulin requirement treatment in patients with adult-onset diabetes


Individual antibody testing would be more appropriate if 1, 2, or 3 of the analytes (GAD65, IA-2, insulin, ZnT8 antibodies) have already been tested and reported negative, and the provider wishes to test for the balance of remaining untested analytes only.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing


Preferred: Red top

Acceptable: Serum gel

Specimen Volume1.5 mL

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
Frozen 28 days
Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Clinical distinction of type 1 from type 2 diabetes mellitus


Identification of individuals at risk of type 1 diabetes (including high-risk relatives of patients with diabetes)


Prediction of future need for insulin treatment in adult-onset diabetic patients

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Islet cell autoantibodies have been known to be associated with type 1 diabetes mellitus for many years. In recent years, several autoantigens against which islet antibodies are directed have been identified. These include the tyrosine phosphatase-related islet antigen 2 (IA-2), glutamic acid decarboxylase 65, zinc transporter 8, and insulin. One or more of these autoantibodies are detected in 96% of patients with type 1 diabetes and are detectable before clinical onset, as well as in symptomatic individuals. A serological study of 50 individuals with type 1 diabetes and 50 control subjects conducted simultaneously across 43 laboratories in 16 countries demonstrated a median sensitivity of 57% and a median specificity of 99% for IA-2 antibody in type 1 diabetes. Prospective studies in relatives of patients with type 1 diabetes have shown that development of 1 or more islet autoantibodies (including IA-2 antibody) provides an early marker of progression to type 1 diabetes. Autoantibody profiles identifying patients destined to develop type 1 diabetes are usually detectable before age 3. In one study of relatives seropositive for IA-2 antibody, the risk of developing type 1 diabetes within 5 years was 65.3%. Some patients with type 1 diabetes are initially diagnosed as having type 2 diabetes because of symptom onset in adulthood, societal obesity, and initial insulin-independence. These patients with "latent autoimmune diabetes in adulthood" may be distinguished from those patients with type 2 diabetes by detection of 1 or more islet autoantibodies (including IA-2).

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

< or =0.02 nmol/L

Reference values apply to all ages.

Provides information to assist in interpretation of the test results

Seropositivity for islet antigen 2 autoantibody (> 0.02 nmol/L) is supportive of:

-A diagnosis of type 1 diabetes

-A high risk for future development of diabetes

-A current or future need for insulin therapy in patients with diabetes

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Negative results do not exclude the diagnosis of or future risk for type 1 diabetes mellitus. The risk of developing type 1 diabetes may be stratified further by testing for antibodies targeting insulin, glutamic acid decarboxylase, and zinc transporter 8 (ZnT8) and human leukocyte antigen genetic markers. Careful monitoring of hyperglycemia is the mainstay of determining the requirement for insulin therapy.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Shields BM, Shepherd M, Hudson M, et al; UNITED study team: Population-based assessment of a biomarker-based screening pathway to aid diagnosis of monogenic diabetes in young-onset patients. et al: Diabetes Care. 2017 Aug;40(8):1017-1025. doi: 10.2337/dc17-0224

2. Bingley PJ: Clinical applications of diabetes antibody testing. J Clin Endocrinol Metab. 2010 Jan;95(1):25-33

3. Bingley PJ, Bonifacio E, Mueller PW: Diabetes Antibody Standardization Program: first assay proficiency evaluation. Diabetes 2003 May;52(5):1128-1136 

4. Christie MR, Roll U, Payton MA, et al: Validity of screening for individuals at risk for type I diabetes by combined analysis of antibodies to recombinant proteins. Diabetes Care. 1997 Jun;20(6):965-970

5. Lampasona V, Petrone A, Tiberti C, et al: Zinc transporter 8 antibodies complement GAD and IA-2 antibodies in the identification and characterization of adult-onset autoimmune diabetes: Non Insulin Requiring Autoimmune Diabetes (NIRAD) 4. Diabetes Care. 2010 Jan;33(1):104-108

Method Description
Describes how the test is performed and provides a method-specific reference

Iodine-125 ([125]I)-labeled recombinant human islet cell antigen (IA-2) is added to the test serum; if antibody is present, it forms a soluble complex with the (125)I-labeled IA-2. Subsequent addition of goat antihuman IgG precipitates the complex. The amount of radioactivity in the precipitate is proportional to the level of antibody in the serum.(Unpublished Mayo method)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

3 to 9 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

28 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
IA2 IA-2 Ab, S 81155-4
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
89588 IA-2 Ab, S 81155-4

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Status - Test Resumed 2021-08-04
Test Status - Test Delay 2021-07-22