Thyroglobulin Antibodies
Also written as: TgAb, Anti-thyroglobulin antibodies
Antibodies against thyroglobulin, the thyroid's storage protein; a marker of autoimmune activity.
What it measures
The level of antibodies directed against thyroglobulin, the large protein the thyroid uses to build and store its hormones. Like TPO antibodies, they are a marker of immune activity against the thyroid gland.
Why a doctor orders it
Often ordered together with TPO antibodies when autoimmune thyroid disease is being considered. It has a second, quite different use: after treatment for certain thyroid cancers it is checked because its presence can interfere with thyroglobulin, a blood test used for monitoring.
What is generally associated with a higher result
Broadly associated with autoimmune thyroid conditions such as Hashimoto's thyroiditis, but also found in a proportion of people with no thyroid problem at all. In thyroid cancer follow-up its main significance is technical - it can make the thyroglobulin monitoring test unreliable.
What is generally associated with a lower result
Low or undetectable levels are the usual finding and are generally not pursued.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Some healthy people, particularly women and older adults, test positive without thyroid disease
- Pregnancy and the months after childbirth
- Laboratory method, since assays and units differ between labs
- Other autoimmune conditions
Questions to take to your appointment
- Why was this checked alongside, or instead of, TPO antibodies?
- If I am being monitored after thyroid surgery, how would this antibody affect the thyroglobulin result?
- What does it usually mean when this antibody is present while thyroid hormone levels are normal?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
Support this site
This site is free, has no paywall, and takes no money from hospitals, insurers, or billing companies. If it helped, a coffee keeps it going.
Buy us a coffee