What is Thyroglobulin Test

Thyroglobulin (Tg) test is used to:

• Monitor the treatment of some types of thyroid cancer.
• Check for a return (recurrence) of previous thyroid cancer.

This test may be done before and after treatment for thyroid cancer. It may then be done at regular intervals to help make sure the cancer has not come back.

The test may also be used to help determine the cause of an overactive thyroid (hyperthyroidism).

What is being tested?

This test measures the amount of thyroglobulin in your blood. Thyroglobulin is a protein that is made in the thyroid gland. It may also be made by certain types of thyroid tumors. Increased levels can indicate a thyroid tumor, the return of a previous tumor, or other problems with the thyroid gland.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

How are the results reported?

Your test results will be reported as a value that indicates the amount of thyroglobulin in your blood. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Age: 12 years and older.
  • Male: 0.5–53.0 ng/mL.
  • Female: 0.5–43.0 ng/mL.
• Age: 1–11 years.
  • Male: 0.6–50.1 ng/mL.
  • Female: 0.5–52.1 ng/mL.
• Age: 0–11 months.
  • Male: 0.6–5.5 ng/mL.
  • Female: 0.5–5.5 ng/mL.

What do the results mean?

Thyroglobulin levels that are higher than the reference ranges may indicate ongoing or recurrent thyroid cancer. There are also many noncancerous (benign) conditions that can lead to higher levels of thyroglobulin. If your test result is abnormal, your health care provider will determine the cause and significance.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• This test measures the amount of thyroglobulin (Tg) in your blood.
• Thyroglobulin levels are tested to monitor treatment and recurrence for some thyroid cancers. The test may also be done to help determine the cause of an overactive thyroid gland.
• Increased thyroglobulin levels can indicate a thyroid tumor, the return of a previous tumor, or other problems with the thyroid gland.
• Talk with your health care provider about what your results mean.