Diagnosis

It's a good idea to see your GP if you have possible symptoms of thyroid cancer.

Your GP will examine your neck and ask about any other symptoms you may be experiencing, such as unexplained hoarseness.

If they think you might have a thyroid problem, they may organise some tests or refer you to a hospital specialist.

The tests you may have are described below.

Blood test

A blood test called a thyroid function test is used to check the levels of thyroid hormones in your blood.

Abnormal levels could mean that you have an overactive thyroid or an underactive thyroid, rather than cancer. 

Further tests, such as an ultrasound scan, will be needed if the test shows that your thyroid hormone levels are normal.

Ultrasound scan

An ultrasound scan uses sound waves to create an image of the inside of your body.

An ultrasound scan of your neck can check for a lump in your thyroid that could be caused by cancer.

If a potentially cancerous lump is found, a biopsy will be done to confirm the diagnosis.

Biopsy

The only way to confirm if a lump on the thyroid is cancer is to take a biopsy. This is where a small sample of cells are removed and studied under a microscope.

A biopsy of the thyroid is usually done by inserting a thin needle into the lump. An ultrasound scan may be done at the same time to guide the needle into the right place.

This is usually done as an outpatient procedure, which means you will not have to spend the night in hospital.

Further tests

If a biopsy finds that you have thyroid cancer, further tests may be needed to check whether the cancer had spread to another part of your body.

The main tests used for this are:

• a CT scan – a type of scan that uses a series of X-rays and a computer to create detailed images of the inside of the body
• a MRI scan – a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body

Stages of thyroid cancer

If you are diagnosed with thyroid cancer, your doctor may give the cancer a stage.

Doctors usually use the TNM system to stage thyroid cancer. This is a combination of letters and numbers that describe its size and how far the cancer has spread.

• T (tumour) – given from 1 to 4, which describes the size of the tumour
• N (node) – given as either 0 or 1, to indicate whether the cancer has spread to nearby lymph glands
• M (metastases) – given as either 0 or 1, to indicate whether the cancer has spread to another part of the body

Knowing the stage of your cancer will help your doctors decide on the best treatment for you.

Find out more about the TNM staging system for thyroid cancer from Cancer Research UK.

Page last reviewed: Sun Aug 2022 Next review due: Wed Feb 2020