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Anti-Thyroglobulin Antibody

Anti-Thyroglobulin, ATG, Anti-Tg, Thyroglobulin Antibody

Test Codes

EPIC: LAB5820, SOFT: ATG

Department

Special Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

Plasma specimens.

Severely lipemic, icteric, or grossly hemolyzed specimens.   

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 6 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday – Friday.
Results available within two business days.

Reference Range

Less than or equal to 20 IU/mL.

Test Methodology

Chemiluminescent Immunoassay.

Interpretation

Autoimmune thyroid disease affects approximately 1% of the population. Subclinical , focal thyroiditis and/or circulating thyroid antibodies can be found in about 15% of otherwise healthy persons who are euthyroid. TPO antibodies may also be found with other thyroid disorders, such as primary myxedema, hyperthyroidism, goiter and thyroid tumors.

Since autoimmune thyroid disease may produce an immunological response to antigens other than thyroglobulin antigens this assay should always be run in conjunction with the thyroid peroxidase (TPO) antibody. In autoimmune thyroid disease, the frequency of positive results with the TPO antibody test has been shown to be higher than with thyroglobulin antibody test. However , in some cases, a positive thyroglobulin antibody test can be obtained while the TPO antibody test results are negative.

In other autoimmune disorders, such as Sjogren's syndrome, systemic lupus erythmatosus (SLE), rheumatoid arthritis (RA), and autoimmune hemolytic anemia, there is a serologic overlap in which positive reactions may occur with the thyroglobulin antibody and TPO antibody tests.

Thyroid antibodies, particularly TPO antibodies, are found in other thyroid disorders and in other autoimmune diseases such as pernicious anemia, myasthenia gravis, SLE, and rheumatoid arthritis.

Thyroid antibodies are rarely found in the sera of normal patients. Two to seventeen percent of the normal population may have low titers of thyroid antibodies with no symptoms of disease. The incidence is higher in women and increases with age.

The presence of thyroid antibody may be indicative of previous autoimmune disease. Patients with low thyroid antibody concentrations (20-500 IU/mL) should be retested periodically as this may be a sign of early autoimmune disease.

Clinical Utility

The Thyroglobulin Antibody and TPO Antibody assays are used to aid in the diagnosis of autoimmune thyroid disease.

CPT Codes

86800

Contacts

Last Updated

4/16/2024