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

Seeing your GP

If you have symptoms of thyroid cancer, you will usually start by seeing your GP, who will examine you. If they are unsure what the problem is, or think your symptoms could be caused by cancer, they will refer you to a hospital for specialist advice and treatment. You should be seen at the hospital within two weeks.

We have separate 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. Then they will examine you. You may have some of the following tests.

Blood tests

It is not possible to diagnose thyroid cancer through a blood test. But you may have blood tests to check your thyroid function and general health.

Ultrasound thyroid 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 sometimes thyroid cancer can spread to the lymph nodes.

Fine needle aspiration (FNA)

A doctor gently passes a small needle into the lump or swelling in your neck. You may have a local anaesthetic to numb the area. Sometimes the doctor uses an ultrasound scanner to help guide the needle to the right area. Then they take a small sample of cells and examine it under a microscope to check whether there are any abnormal cells.

If an FNA does not collect enough cells, the doctor may want to do it again.

Core biopsy

Very occasionally you may need to have a core biopsy. You have a local anaesthetic to numb the area. Sometimes a general anaesthetic is used. Your doctor uses a needle to take a sample of tissue. The needle is slightly bigger than the one they use for the FNA. They may use an ultrasound scanner to guide the needle to the right area. You may have a core biopsy if:

  • the FNA doesn’t collect enough cells
  • the doctor who looks at the cells from the FNA under the microscope (pathologist) is not sure whether there are cancer cells present.

If you need to have surgery to remove all or part of your thyroid gland, your doctor may suggest you have the surgery straight away rather than having a core biopsy.

Further tests for thyroid cancer

If the tests show that 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 whether it has spread to other parts of the body. This is called staging and will help you and your doctor decide on the best treatment for you. You may have these tests after surgery.

Tests may include:

  • MRI (magnetic resonance imaging) scan

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

  • CT (computerised tomography) scan

    CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. If you are given this, it may affect treatment with radioactive iodine. Your doctor or specialist nurse will be able to discuss this with you.

  • PET-CT scan

    PET-CT scan is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

  • Vocal cord check

    Your doctor will 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 they can be damaged during surgery.

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