Diagnosis of thyroid cancer
A doctor may do different tests to diagnose thyroid cancer. You usually start by visiting your GP and then may have further tests such as an ultrasound or a fine needle aspiration.
At your GP surgery
If you have symptoms of thyroid cancer you usually start by visiting your GP. Your GP will examine the lump or swelling in your neck and ask about any other symptoms you might have. A lump in the thyroid is sometimes called a nodule.
They usually do some blood tests to check how well your thyroid is working. These are called thyroid function tests. They can help to diagnose problems like hyperthyroidism or hypothyroidism.
Your GP will refer you to a hospital for specialist advice and treatment if they:
- are unsure what the problem is
- think your symptoms could be caused by thyroid cancer.
If they think it could be cancer, you should have a hospital appointment. This is usually within 2 weeks.
You might be referred to:
- a specialist called an endocrinologist
- a thyroid surgeon
- an ear, nose and throat (ENT) surgeon.
These are healthcare professionals who diagnose and treat the thyroid gland.
Sometimes a thyroid lump shows up on a scan you may be having for another reason.
The information here is about papillary and follicular thyroid cancers. We have more information about how medullary thyroid cancer (MTC) and anaplastic thyroid cancer are diagnosed.
Getting support
Macmillan is here to support you. If you would like to talk, you can:
- Call the Macmillan Support Line for free on 0808 808 00 00.
- Chat to our cancer information specialists online.
- Visit our Online Community thyroid cancer forum to talk to people who have been affected by thyroid cancer, share your experience, and ask an expert your questions.
At the hospital
The doctor will ask you about your general health, family history and any previous medical problems you have had. They will also examine you. You may have some of the following tests.
Blood tests
It is not possible to diagnose thyroid cancer through blood tests. But you usually have blood tests to:
- check the levels of your thyroid hormone levels which show how well your thyroid is working – for example they may check the levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH)
- check your general health by monitoring how well organs like your kidneys and liver are working
- check your full blood count by measuring levels of different blood cells in your blood.
Ultrasound scan
An ultrasound scan uses sound waves to build up a picture of the inside of the neck and the thyroid gland. Your doctor will also check the lymph nodes in your neck to see if any of them are abnormal. This is because thyroid cancer can sometimes spread to the lymph nodes.
You lie on your back for the scan. When you are lying comfortably, the person doing the scan spreads a gel over your neck. They move a small hand-held device, like a microphone, around the skin on your neck area. A picture of the inside of your neck shows up on a screen.
An ultrasound scan only takes a few minutes and is painless.
The results of the ultrasound scan help the doctors decide if you need a fine needle aspiration biopsy (FNA). Doctors look at different things to assess whether you need a FNA. You might be more likely to need one if the lump:
- looks solid rather than fluid-filled on the ultrasound
- has irregular margins
- shows tiny white calcium dots in the nodule.
Fine needle aspiration (FNA)
A doctor gently passes a small needle into the lump or swelling in your neck. Sometimes the doctor uses an ultrasound scan to help guide the needle to the right area. They take a small sample of cells and examine it under a microscope, to check for any abnormal cells.
You might need a FNA fine done again if:
- it does not collect enough cells
- the results are not clear enough to make a diagnosis.
Or your doctor might advise that you have another type of biopsy called a core needle biopsy.
Core needle biopsy
You have a local anaesthetic to numb the area so you should not feel any pain. Your doctor uses a needle slightly bigger than the one used for the FNA to take a sample of tissue from the lump. They use an ultrasound scan to guide the needle to the right area.
After a biopsy
If the biopsy result shows cancer cells your doctor can usually tell you the type of thyroid cancer you have.
Sometimes it is not possible to tell the difference between a non-cancerous and a cancerous nodule by biopsy alone. Your doctor may advise you to have surgery. This is usually to remove the side of the thyroid where the lump is to help make a diagnosis.
Doctors may also arrange molecular tests on the cancer cells to help diagnose thyroid cancer.
Further tests for thyroid cancer
If the tests show you have thyroid cancer, you may have further tests. These are to find out the size and position of the cancer, and if it has spread to other parts of the body. This is called staging.
We have more information about staging and grading of:
Knowing the stage of the cancer helps you and your doctor decide on the best treatment for you. You might have some of the following tests after surgery. Not everyone will need further scans.
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CT scan
A CT scan makes detailed pictures of the inside of the body using x-rays taken by the CT scanner. The scan takes 10 to 30 minutes and is painless.
You may have an injection of a dye called a contrast. It helps show certain areas of the body more clearly.
If your treatment for thyroid cancer is going to include radioactive iodine, a CT contrast may affect when you can have this treatment. Your doctor or specialist nurse will discuss this with you.
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MRI scan
An MRI scan uses magnetism to build up a detailed picture of areas of the body. You have the scan in the x-ray department of a hospital. During the scan, you need to lie still on a bed inside a long cylinder (tube).
The scan usually lasts between 15 minutes and 1 hour. It is painless, but you may find it uncomfortable to lie still for that long.
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PET-CT scan
A PET scan uses low-dose radiation to check the activity of cells in different parts of the body. You may have a PET scan and a CT scan together. This is called a PET-CT scan. It can give more detailed information about cancer or abnormal areas seen on other scans.
About 1 hour before the scan, the radiographer will inject a radioactive substance into a vein, usually in your arm. This is called a tracer. The scan takes about 30 to 60 minutes. You lie still on a narrow bed which moves slowly backwards and forwards through the scanner.
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Tests on the cancer cells (molecular testing)
Your doctor may also arrange tests to look for certain gene changes (mutations) in the thyroid cancer cells. This is called molecular testing.
The results might help to diagnose thyroid cancer and affect the type of cancer drug treatment you have. If the cancer cells show a gene change in the NTRK, RET or BRAF gene you might have treatment with targeted therapy drugs if you need them.
About our information
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.
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References
Below is a sample of the sources used in our thyroid cancer information. If you would like more information about the sources we use, please contact us at
informationproductionteam@macmillan.org.uk
National Institute for Health and Care Excellent (NICE). [NG230]. Thyroid cancer: assessment and management. Published: 19 December 2022. Available from: www.nice.org.uk/guidance
Datta, R. British Medical Journal Best Practice Guidelines, Thyroid cancer. 2023. British Medical Journal. Available from: www.bestpractice.bmj.com/topics/en-gb/263
European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019. Available from: www.annalsofoncology.org/article/S0923-7534(20)32555-2/fulltext
Date reviewed
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