Tests for thyroid cancer

You usually have a number of tests to check for thyroid cancer. If you have cancer these tests can also help your doctor decide what treatment you need. These tests include:

  • an ultrasound scan Open a glossary item to create a picture of your thyroid gland Open a glossary item
  • a test to look at a sample of cells from your thyroid (biopsy Open a glossary item)
  • scans to find out if your cancer has spread (CT scan Open a glossary item or MRI scan Open a glossary item)

Tests your GP might do

Most people start by seeing their GP. Your GP can do some tests to help them decide whether you need to see a specialist. Your GP might:

  • feel around your neck and do a general examination of your body
  • arrange blood tests to assess how well your thyroid gland is working

Blood tests

Blood tests won’t find or diagnose thyroid cancer. But they will help to show how well your thyroid gland is working. Your doctor might organise tests to check levels of:

  • thyroid stimulating hormone (TSH)
  • T3 and T4 hormones
  • calcitonin

You might also have blood tests to check your full blood counts, and your liver and kidney function.

Tests at the hospital

If your GP thinks there’s any chance your symptoms could be due to thyroid cancer, you will have further tests at the hospital. These might include:

  • an ultrasound scan of your neck
  • taking a sample of cells from your thyroid gland (biopsy)
  • an MRI scan
  • a CT scan
  • blood tests

Ultrasound scan of your neck

An ultrasound scan uses high frequency sound waves to create a picture of a part of the body. The ultrasound scanner has a microphone that gives off sound waves.

The sound waves bounce off the organs inside your body, and the microphone picks them up. The microphone links to a computer that turns the sound waves into a picture on the screen.

Your doctor uses the scan to:

  • look at your thyroid and neck to see if there are lots of lumps or just one
  • see if the lumps are solid or filled with fluid (cysts)

A sonographer usually does the ultrasound scan in the hospital x-ray department. The results help the doctors decide whether they need to take a sample of tissue (biopsy).


A biopsy means taking small tissue samples from your thyroid gland. The doctor sends the samples to a laboratory and a pathologist looks at them under a microscope to check for cancer.

The doctor puts a small needle into the lump or swelling. They might use an ultrasound scan to find the right place to take the sample.

There are different types of biopsies. You might have:

  • a fine needle aspiration (FNA) – this is also called fine needle aspiration cytology (FNAC)
  • a core biopsy

Sometimes the doctors are unable to make a diagnosis after the first biopsy. This might be because they did not get enough cells. Or sometimes it is difficult for the pathologist to be certain whether the cells are cancer or not cancer (benign).

In this situation, you might need to have another FNA. Or the doctor might do a core biopsy which uses a slightly larger needle.

If the biopsy results remain unclear, you might need to have surgery to remove some of your thyroid gland. This operation is called a diagnostic hemithyroidectomy. The surgeon removes:

  • half of your thyroid gland (one lobe)
  • the bridge of thyroid tissue connecting the 2 thyroid lobes (the isthmus)

Testing your cancer cells for gene changes

Your doctor sometimes does tests on your thyroid cancer cells. These are to look for changes in certain genes. Open a glossary item

You might hear these tests called cytogenetic tests or molecular analysis. The doctors are looking for changes in genes and chromosomes in the cancer cells. 

Your doctor might do these tests:

  • to help diagnose your cancer if the biopsy results are unclear - certain gene changes make a cancer diagnosis more likely
  • to look for certain gene changes that might help the doctor choose targeted treatments

The doctor can do genetic tests on tissue samples from your biopsy or surgery. Or they might be able to do a blood test.

CT scan

A CT scan is a test that uses x-rays and a computer to create detailed pictures of the inside of your body. It takes pictures from different angles. The computer puts them together to make a 3 dimensional (3D) image.

You might have a CT scan to find out how big the cancer is, and whether it has spread.

MRI scan

MRI stands for magnetic resonance imaging. An MRI is a type of scan that creates pictures using magnetism and radio waves. It produces pictures from angles all around the body and shows up soft tissues very clearly.

You might have an MRI scan to:

  • find out how big the thyroid cancer is and whether it has spread into the surrounding area
  • look at the lymph nodes in your neck
  • find out if cancer has spread to other parts of your body

In some situations, your doctor may suggest an MRI if a CT scan hasn't been able to give all the information they need. You might have an injection of a special dye (contrast medium) before the scan to help make the pictures clearer.

PET-CT scan

A PET-CT scan combines a CT scan and a PET scan. It gives detailed information about your tumour.

The CT scan takes a series of x-rays from all around your body and puts them together to create a 3 dimensional (3D) picture. The PET scan uses a mildly radioactive drug to show up areas of your body where cells are more active than normal. 

You don't usually have a PET-CT scan to diagnose or stage thyroid cancer. But you might have one after your treatment for thyroid cancer.


The tests you have helps your doctor find out if you have thyroid cancer. They can find out what type it is and whether it has spread (the stage).

This is important because doctors recommend your treatment according to the type and stage of the cancer.

Coping with thyroid cancer

Coping with a diagnosis of thyroid cancer can be difficult. There is help and support available to you and your family.

  • Thyroid cancer: assessment and management 
    National Institute for Health and Care Excellence (NICE), 2022

  • Thyroid cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    S Filetti and others
    Annals of Oncology, 2019. Volume 30, Issue 12, Pages 1856–1883

  • Management of thyroid cancer: United Kingdom National Multidisciplinary Guidelines
    A L Mitchell and others
    Journal of Laryngology and Otology, 2016. Volume 130, Supplement 2, Pages 150 to 160

  • British Thyroid Association Guidelines for the Management of Thyroid Cancer
    P Perros and others
    Clinical Endocrinology, 2014. Volume 81, Supplement 1, Pages 1-122

Last reviewed: 
19 Jul 2023
Next review due: 
19 Jul 2026

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