- When to take the exam
- How to interpret the result
- High thyroglobulin
- Low thyroglobulin
- How it is done and how it should be prepared
Thyroglobulin is a tumor marker widely used to assess the development of thyroid cancer, especially during its treatment, helping the doctor to adapt the form of treatment and / or the doses, according to the results.
Although not all types of thyroid cancer produce thyroglobulin, the most common types do, and as a result, 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 rarer cases, the thyroglobulin test can also 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 base value for comparison and then repeated several times over time to assess whether the chosen form of treatment has resulted in cure of cancer.
If you have chosen to have surgery to remove the thyroid, this test is also done frequently after the surgery to ensure that no cancer cells are left in the site, which may be developing again.
In addition, in some cases of suspected hyperthyroidism, the doctor may also order a thyroglobulin test to identify diseases such as thyroiditis or Graves' disease, for example.
See which tests evaluate the thyroid and when to do it.
How to interpret the result
The thyroglobulin value in a healthy person, without any change in the thyroid, is generally less than 10 ng / mL but can be up to 40 ng / mL. So if the test result is above these values, it can indicate the presence of a thyroid problem.
Although the test result must always be interpreted by the doctor who ordered it, the results usually mean:
High thyroglobulin
- Thyroid cancer; Hyperthyroidism; Thyroiditis; Benign adenoma.
If any 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 cancer cases, this test is not intended to confirm the presence of cancer. In suspected cases, it is still necessary to have a biopsy 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 a thyroid disorder, when the value drops, it means that the cause is being treated and that is why the gland is producing less thyroglobulin.
However, if there was no suspicion of a thyroid problem and the value is very low, it may also indicate a case of hypothyroidism, although it is more rare.
How it is done and how it should be prepared
The test is done in a very simple way, it being only necessary to collect a small blood sample from the arm.
In most cases, no preparation is necessary, but depending on the technique used to perform the test, some laboratories may recommend that you stop taking some vitamin supplements, such as those containing vitamin B7, for at least 12 hours before of the exam.
