Diagnosis of thyroid cancer

There are different tests a doctor may use to diagnose thyroid cancer, including an ultrasound and a fine needle aspiration.

Seeing your GP

If you have symptoms of thyroid cancer, you will usually start by seeing your GP, who will examine you. They 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 cancer.

If they think it could be cancer, you should be seen at the hospital within 2 weeks.

The information here is about papillary and follicular thyroid cancers. We have more information about how medullary thyroid cancer and anaplastic thryoid cancer are diagnosed.

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 your general health and your thyroid hormone levels. These levels show how well your thyroid is working.

Ultrasound thyroid scan

An ultrasound 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 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 to decide whether a fine needle aspiration biopsy (FNA) is needed.

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.

If an FNA does not collect enough cells, it may need to be done again.

Core biopsy

Sometimes you may need to have a core biopsy. You have a local anaesthetic to numb the area. Your doctor uses a needle to take a sample of tissue from the lump or swelling in your neck. The needle is slightly bigger than the one used for the FNA. They may use an ultrasound scan to guide the needle to the right area. You may have a core biopsy if:

  • the FNA does not collect enough cells
  • the results from the FNA are not clear enough to make a diagnosis.

Further tests for thyroid cancer

If the tests show you have thyroid cancer, your specialist may want to do some 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. Knowing the stage of the cancer helps you and your doctor decide on the best treatment for you. You may have these tests after thyroid cancer surgery

Tests may include the following.

  • CT scan

    CT scan takes a series of x-rays. These build up a detailed picture of the inside of the body.

  • MRI scan

    An MRI scan uses magnetism to build up a detailed picture of areas of your body.

  • PET-CT scan

    PET-CT scan uses low-dose radiation to check the activity of cells in different parts of the body. A PET scan is sometimes given together with a CT scan. This is called a PET-CT scan. It can give more detailed information about cancer or abnormal areas seen on x-rays, CT scans or MRI scans.

  • Vocal cord check

    Your doctor may need to check your vocal cords before and after surgery to remove your thyroid gland. This is because the nerves that control your vocal cords are close to the thyroid gland, and can be damaged during thyroid cancer surgery.

About our information

  • 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 cancerinformationteam@macmillan.org.uk

    British Medical Journal. Best Practice Guidelines, Thyroid cancer. 2020.

    European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019.

    National Institute for Health and Care Excellence (NICE). TA535: Lenvatinib and Sorafenib for treating differentiated thyroid cancer after radioactive iodine. 2018. www.nice.org.uk/guidance/ta535 [accessed May 2021].

  • Reviewers

    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. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We try to make sure our information is as clear as possible. We use plain English, avoid jargon, explain any medical words, use illustrations to explain text, and make sure important points are highlighted clearly.

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