What is the Thyroglobulin test?

Frequently Asked Questions:

What is the thyroglobulin test used for?

Doctors use the thyroglobulin test as a check of carcinogenic cells post-treatment, for thyroid cancer. After one year of surgery, if the thyroglobulin levels continue to rise, it is an indication that the cancer has returned. If levels remain undetectable, the risk of return is low. The thyroglobulin test is used as a measure to monitor the status of the already detected thyroid cancer, and not as a primary detection tool.

Understanding the test results of the thyroglobulin test.

• If the test results of the thyroglobulin levels are high or have increased, this is an indication of the growth or spread of the thyroid cancer cells.
• If the thyroglobulin levels decreased initially, but then increased over time, it is an indication of the return of cancer, despite successful treatment.
• If the thyroglobulin levels are minute, this indicates successful and complete treatment of cancer cells. 

Why do I need a thyroglobulin test?

If you have been treated for thyroid cancer, your doctor will prescribe a thyroglobulin test to keep a check on the cancer cells. Shortly after the treatment, you will be tested regularly, with the frequency of tests reducing as time progresses. Once the thyroid has been removed, the bloodstream needs to be checked for residual levels of thyroglobulin. 

What happens during the thyroglobulin test?

A thyroglobulin test is like a simple blood test. During the test, the doctor or health care provider will insert a needle and draw a small vial of blood that will be sent to the laboratory for testing. Quite painless, there are no side effects to the test. The entire process should not take more than 5 minutes.

What is the normal level of thyroglobulin?

The normal thyroglobulin range in healthy people without the thyroglobulin antibody (TgAb) ranges from 3-40 ng/mL. Women tend to have slightly higher thyroglobulin levels as compared to men. The range of acceptable thyroglobulin levels might be higher in countries where there is an iodine deficiency.

What are the symptoms of high thyroglobulin?

Some common symptoms indicative of high thyroglobulin levels are:

• Unexplained weight gain/loss
• Constipation 
• Dry and coarse skin
• Fatigue and unexplained tiredness
• Insomnia
• Goitre

What is considered a high thyroglobulin level?

3-40 ng/mL is considered to be the normal thyroglobulin levels in a healthy person. Any reading of more than 40 ng/mL is considered to be a high level of thyroglobulin in the bloodstream. This is indicative that the cancer cells have started to grow and/or are spreading in the body. Measures must be taken immediately to control the same.

What does positive thyroglobulin mean?

A positive thyroglobulin test is indicative of growing and spreading cancer cells. Post the thyroid surgery, there should be no thyroglobulin present in the bloodstream. If the thyroglobulin test shows the presence of the protein, the cancer is growing. An ultrasound of the neck area will help to confirm the same.

Does a thyroglobulin test require fasting?

No, the thyroglobulin test does not require fasting. There are no preparations that the patient must make in advance. However, it is advised to not consume any multivitamins and biotin (vitamin B7) for 12 hours before giving the test as it could interfere with the results. There are no side effects to the thyroglobulin test either.

What causes high thyroglobulin levels?

The size of the thyroid gland affects the levels of thyroglobulin found in the bloodstream. High thyroglobulin levels are caused due to the presence of disorders like cancer, nodules, or autoimmune diseases that reduce the size of the thyroid.

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