What is this test?
Thyroglobulin is a protein produced only by thyroid tissue. It is most often used for follow-up after treatment of certain differentiated cancers of the gland.
Why might it be ordered?
- For follow-up after surgery and other treatment of papillary or follicular thyroid cancer.
- In selected situations, to assess remaining thyroid tissue when requested by a specialist.
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?
Report previous treatment, including the date of surgery or radioactive iodine, and the timing of thyroid hormone medicines. Anti-Tg is usually measured at the same time. 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 time trend in the same method is more informative than a single value. Anti-Tg can make the result inaccurate. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.