Thyroglobulin (Tg)

Thyroglobulin is a protein, which is produced by the follicle cells in the thyroid gland. The thyroid gland is very important as it helps to control the body’s metabolic processes. Thyroglobulin is stored in the thyroid gland before being broken down into thyroid hormones known as T3 and T4; the production of the hormones is controlled by the pituitary hormone, thyroid stimulating hormone (THS). Many forms of thyroid cancer lead to production of thyroglobulin.

When is the test used?

The test is used to monitor the condition of patients who have been diagnosed with thyroid cancer; the test can give doctors an idea of how effectively the treatment is working and can also indicate early signs that a tumour has recurred. The test may be repeated on a regular basis to monitor the patient’s condition and check for early signs of recurrence.

The test is usually ordered after surgery to remove the thyroid gland; this enables doctors to assess whether all the cancerous tissue has been removed. The test will be repeated to check for signs of recurrence.

How is the test done?

The test is done by taking a sample of the patient’s blood; the blood is usually taken from a vein on the inside of the elbow. The blood is drawn out and collected using a needle and a syringe. When the doctor (or nurse) has a sufficient sample, the blood will be bottled, labelled with the patient’s name and sent off to the laboratory for analysis.

What do the test results mean?

Healthy individuals may have small quantities of thyroglobulin in their blood. If a patient has had their thyroid gland removed, the levels of thyroglobulin should be undetectable. If the test result is positive, this may indicate that some of the cancerous tissue is still present; further tests will usually be ordered if this is the case. If levels are very low after treatment and then start to rise, this may indicate that the cancer has come back and further tests will usually be carried out.

Specific Blood Tests

© Medic8® | All Rights Reserved