What does the Thyroglobulin Antibodies test measure?

Why is Thyroglobulin Antibodies measured?

Anti-Tg is less sensitive than anti-TPO but often coexists in Hashimoto thyroiditis. Its principal clinical role is in the follow-up of differentiated thyroid cancer, where it can interfere with immunometric thyroglobulin assays and produce falsely low or undetectable results. When positive, liquid chromatography–tandem mass spectrometry thyroglobulin measurement may be required for accurate tumour-marker surveillance.

Reference ranges

Standard reference

Typically <40 IU/mL; positive if above the laboratory threshold.

Functional medicine optimal

Absence of detectable antibody. Positive anti-Tg without anti-TPO may still signal autoimmune thyroid disease, though it is less specific.

Units

IU/mL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.