What is this test?
Anti-Tg are antibodies against thyroglobulin, a protein of the thyroid gland. They can support the evaluation for an autoimmune thyroid process.
Why might it be ordered?
- To clarify an autoimmune cause of abnormal thyroid function.
- For the correct interpretation of thyroglobulin in follow-up after treatment of differentiated thyroid cancer.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
The result is examined with TSH, FT4, Anti-TPO and, if necessary, thyroglobulin. A positive result means the tested antibodies were detected, but it does not establish a diagnosis on its own. A negative result does not rule out every autoimmune condition.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.