What it measures
- Thyroglobulin
What is thyroglobulin used for?
Thyroglobulin is a protein made only by thyroid cells. After the thyroid has been removed or treated for differentiated thyroid cancer, thyroglobulin should be very low or undetectable, so measuring it over time helps your specialist watch for any return of the condition.
Thyroglobulin isn’t a screening test for thyroid cancer, as it can be raised in many harmless thyroid conditions. If you have symptoms such as tiredness or weight change, a Thyroid Function test is usually the better first step.
Thyroglobulin antibodies, present in some people, can interfere with the result, so your specialist will usually interpret it alongside an antibody test.
Who it’s for
- Follow-up after thyroidectomy or radioiodine treatment, as requested by your consultant
- Investigating some thyroid conditions alongside other tests
How to prepare
- Drink plenty of water beforehand; it makes the sample quicker and easier to take.
- You don’t need to fast.
- Stop biotin (vitamin B7) supplements 48 hours before, as biotin can affect hormone and thyroid results.
Thyroglobulin Blood Test: your questions
Is thyroglobulin a test for thyroid cancer?
Not on its own. It’s mainly used to monitor people who have already been treated for differentiated thyroid cancer, not to diagnose it.
Information on this page is general and doesn’t replace advice from your GP, midwife or consultant. If you feel unwell or are worried about symptoms, contact your GP, call NHS 111 or, in an emergency, 999.