What is the test for Thyroglobulin?

Thyroglobulin is a tumor marker widely used to evaluate the development of thyroid cancer, especially during its treatment, helping the doctor to adapt the form of treatment and / or doses, according to the results.

Although not all types of thyroid cancer produce thyroglobulin, the most common types produce and therefore the levels of this marker are usually increased in the blood in the presence of cancer. If the thyroglobulin value continues to increase over time, it means that the treatment is not having the desired effect and needs to be changed.

In rare cases, the thyroglobulin test can still be used to determine the cause of hyperthyroidism or hypothyroidism, for example.

When to take the exam

The thyroglobulin test is usually done before starting any treatment for thyroid cancer so that there is a baseline value for comparison and then repeated several times over time to assess whether the form of treatment chosen is having a cure of cancer.

If you have opted for surgery to remove the thyroid, this test is also done frequently after surgery to ensure that there are no cancer cells left in the site that may be developing again.

In addition, in some cases of suspected hyperthyroidism, the doctor may also order the thyroglobulin test to identify diseases such as thyroiditis or Graves' disease, for example.

Here are the tests that evaluate the thyroid and when to do it.

How to interpret the result

The thyroglobulin value in a healthy person with no thyroid abnormality is usually less than 10 ng / mL but may be as high as 40 ng / mL. So if the test result is above these values, it may indicate the presence of a thyroid problem.

Although the test result should always be interpreted by the doctor who asked for it, the results usually means:

High Thyroglobulin

• Thyroid cancer;
• Hyperthyroidism;
• Thyroiditis;
• Benign adenoma.

If some type of cancer treatment has already been done, if the thyroglobulin is high it may mean that the treatment has had no effect or that the cancer is developing again.

Although thyroglobulin is increased in cases of cancer, this test does not confirm the presence of cancer. In cases of suspicion, biopsy is still needed to confirm the cancer. See the main symptoms of thyroid cancer and how to confirm the diagnosis.

Low thyroglobulin

Since this test is done on people who already have some thyroid changes, when the value goes down, it means the cause is being treated and so the gland is producing less thyroglobulin.

However, if there was no suspicion of a thyroid problem and the value is too low it may also indicate a case of hypothyroidism, although it is rarer.

How it is done and how it should be prepared

The examination is done very simply, and it is only necessary to collect a small sample of blood from the arm.

In most cases, no preparation is required, but depending on the technique used to take the test, some laboratories may recommend stopping the intake of some vitamin supplements, such as those containing vitamin B7, for at least 12 hours before of the examination.