Test Details
Thyroglobulin Antibody (Anti-Tg)
An antibody directed against the thyroid-specific protein thyroglobulin (Tg). Increased antibody levels are often associated with thyroiditis including Hashimotos, Graves, and post-partum thyroditis.
Methodology
Electrochemiluminescent Immunoassay
Patient Preparation
High doses of biotin may interfere with Thyroglobulin Antibody assay results. Patients should refrain from biotin consumption for 3 days prior to sample collection.
Preferred Specimen
1.0 mL serum collected in a serum separator tube (SST / Tiger Top)
Alternate Specimen
1.0 mL plasma collected in a plasma separator tube (PST/Pearl Top)
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 4 days
Lab Values
Thyroglobulin Antibody (Anti-Tg)
- Optimal: <15 IU/mL
- Borderline: 15-115 IU/mL
- Increased Risk: >115 IU/mL
Clinical Significance
Thyroglobulin Antibody (Anti-Tg)
Tg antibodies are mainly used to evaluate a diagnostic suspicion of autoimmune thyroiditis, and are usually requested together with TPO antibodies. Tg antibodies are polyclonal antibodies to Tg with a prevalence of 20%–90% in Hashimoto thyroiditis and 30%–60% in Graves disease, but, like TPO Abs, they are also present in 10%–27% of healthy adults. Tg antibodies are less common and of lower titer than TPO antibodies. The majority of patients with Hashimoto’s thyroiditis have TPO and/or Tg antibodies, such that a negative antibody result has a high negative predictive value. The titer of Tg antibodies does not usually correlate with the degree of thyroid dysfunction.
References:
- Burek CL, Rose NR, Caturegli P. Thyroglobulin, thyroperoxidase, and thyrotropin-receptor autoantibodies. In Autoantibodies (second edition), 2007. Science Direct: https://doi.org/10.1016/B978-044452763-9/50055-X
Treatment Options
Thyroglobulin Antibody (Anti-Tg)
Treatment is based on etiology of elevation and clinical symptoms.
