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Thyroglobulin Antibodies (Tg-Ab)

Published: July 27, 2026Updated: August 25, 2026

This biomarker measures the level of antibodies against thyroglobulin, a protein produced by the thyroid gland, in the blood.

Quick summary

Tg-Ab testing helps diagnose autoimmune thyroid conditions like Hashimoto's thyroiditis and Graves' disease.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
IU/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Anti-Tg, Abbott Anti-Tg, Siemens Anti-Tg
interpretation: {"text":"0–20 IU/mL: No significant autoimmune thyroid disease detected.","label":"Normal"}; {"text":">20 IU/mL: Possible autoimmune thyroid disease; further evaluation required.","label":"Elevated"}

Thyroglobulin antibodies (Tg-Ab) are autoantibodies that target thyroglobulin, a protein essential for thyroid hormone production. Elevated levels of Tg-Ab in the blood indicate an autoimmune response against the thyroid gland.

The presence of Tg-Ab is commonly associated with autoimmune thyroid diseases such as Hashimoto's thyroiditis and Graves' disease. Testing for these antibodies aids in the diagnosis and management of these conditions.

Typically, levels below 20 IU/mL are considered normal. Higher values may suggest an autoimmune thyroid disorder, prompting further clinical evaluation and management.

Frequently asked questions

What does a high Tg-Ab level mean?
A high Tg-Ab level indicates an autoimmune response against the thyroid, suggesting conditions like Hashimoto's thyroiditis or Graves' disease.
Can Tg-Ab levels change over time?
Yes, Tg-Ab levels can fluctuate with disease activity and treatment, making them useful for monitoring autoimmune thyroid conditions.
  1. 1
    American Thyroid AssociationSource
  2. 2
    Mayo ClinicSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy