26 Feb 2024
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Thyroid Cancer Forum UK

Thyroid Cancer Forum UK

Thyroid Cancer
Forum UK


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Thyroid Cancer Diagnosis

Initial Tests

Blood Tests

Thyroid function tests (TFTs): this test checks the level of thyroid hormones in the blood. It is usually requested whenever someone first presents to their doctor with a thyroid swelling. It is a helpful test to see if the thyroid gland is working normally. This test is usually normal if thyroid cancer is present.

Calcitonin: this test can help diagnose medullary thyroid cancer as there is a high level of this hormone in the blood in this disease. This test is not helpful for other types of thyroid cancer and is not usually done until after the tests mentioned below.

Fine needle aspiration cytology (FNAC)

This involves a small needle being inserted through the skin into the thyroid gland lump or into lymph glands/nodes in the neck to remove some cells. This can either be done in the routine clinic or may be done with the help of an ultrasound scan.

The sample of cells is then looked at with a microscope to see if there are any signs of thyroid cancer present.

The test is most useful when cancer cells can be seen. If the test does not show any cancer cells, this does not necessarily mean cancer is not present, as not all types of cancer can be diagnosed with this test. Follicular thyroid cancer cannot be diagnosed by FNAC in which case a diagnostic thyroid lobectomy (removal of the abnormal lobe) will need to be performed so that the whole thyroid nodule can be examined in the laboratory in order to reach a diagnosis.

This test may need to be repeated if the first sample is not helpful. The test may also be negative if the needle does not pick up any cancer cells.


Sometimes a FNAC result will not be helpful and a core biopsy or very occasionally a surgical biopsy may be needed. If this is needed the doctor would explain in more detail what it would entail and whether any anaesthetic is required.

Thyroid Ultrasound scan (USS)

This test uses gel and a probe rubbed over the neck to look at the size and texture of the thyroid gland and the lymph glands/nodes in the neck. It can show if there are any lumps in the thyroid gland, if the lumps are solid or fluid containing and if the lymph glands/nodes look normal in shape and size. If anything shows up it is possible to use the ultrasound probe and pictures to guide the needle used for a FNA (see above).

Other investigations/tests

CT (Computerised Tomography) or MRI (Magnetic Resonance Imaging)

These 2 types of scan show a 3 dimensional picture of the inside of the body. They are not always required but can be helpful to show if the cancer is growing outside of the thyroid gland and can provide more information on the lymph glands/nodes and other parts of the body such as the lungs, liver and bones.

Thyroid radionucleotide or radioisotope scans

This test is no longer commonly done. It involves an injection of a small amount of radioactive liquid (either iodine or technetium) into an arm vein followed by a scan about 20 minutes later. The scan pictures are taken using a gamma camera x ray machine which is positioned over the neck area.

PET (Positron Emission Tomography) scan

This is another type of radioactive scan. It is not so widely available in the UK as the other types of scan discussed above. It is rarely needed at the time of thyroid cancer diagnosis but might be useful during the follow up period of a small number of patients when other x ray tests have not been helpful.

More information on some of these x-ray (radiology) examinations can be found at www.goingfora.com/radiology


This is used to describe the size of the thyroid cancer and whether it has spread outside the thyroid gland to involve the lymph glands/nodes or other parts of the body.

The mostly commonly used staging system is called ‘TNM’. This stands for Tumour, Nodes and Metastases.

There are 4 T-stages (1-4) and this describes the size of the tumour in relation to the thyroid gland.

N describes whether the cancer has spread to the lymph nodes/glands close to the thyroid gland.

M describes whether the cancer has spread to other parts of the body, such as the lungs or bones, to produce ‘secondaries’.

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Thyroid Cancer Forum UK

Dr. Kate Garcez
Christie NHS Foundation Trust, Manchester, M20 4BX

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