Thyroid Cancer Diagnosis

Physicians go through a variety of tests and procedures to arrive at a thyroid cancer diagnosis. Some of the most common diagnostic steps include:

  • Blood tests
  • Imaging tests
  • Medical and family history exploration
  • Needle biopsy
  • Physical exam of the thyroid.

Medical History and Physical Exam

If you think you have a thyroid problem, your doctor will first ask you about your personal medical history to learn more about your risk factors, symptoms and general health concerns. Since exposure to radiation is a known risk factor for thyroid cancer, your doctor will need to know about any prior exposure to radiation. And because some thyroid problems have a hereditary component, your doctor will want to know if anyone in your family has had, for example, medullary thyroid cancer or any other thyroid diseases.

The doctor will check your neck for lumps and possible thyroid nodules and examine the size and firmness of your thyroid, also checking the surrounding lymph nodes for signs of swelling.

Thyroid Blood Tests

Healthy thyroids produce thyroid hormones in amounts that meet the body’s needs. Blood tests for thyroid-stimulating hormones (TSH) and the T3 and T4 thyroid hormones help doctors assess how well your thyroid is functioning, and may determine the need for imaging tests to look for thyroid nodules. Blood tests for calcitonin — a hormone that regulates calcium levels in the blood — can indicate the presence of medullary thyroid carcinoma, although no blood tests can conclusively determine whether a thyroid nodule is cancerous.

Ultrasound and Imaging Tests

Tests used to see if an area is cancerous, if cancer has spread or if cancer has returned include:

  • CT scans and MRIs: These are used to see the size and location of thyroid cancer cells, and whether the cancer has spread to nearby areas.
  • Radioiodine tests: These are used to find out if thyroid cancer has spread — based on the fact that thyroid cells take up iodine.
  • Ultrasound: Ultrasounds use sound waves to create an image of the body. They help to determine the number and size of thyroid nodules and if they’re filled with fluid, and to help doctors locate nodules for biopsy. While ultrasound can’t say definitively if a nodule is or is not cancerous, it can help determine whether or not cancer has spread to surrounding lymph nodes.

Needle Biopsy

The definitive test for a thyroid cancer diagnosis involves taking a biopsy of suspicious cells, studying these cells under a microscope by a pathologist and determining whether the cells are cancerous. Fine needle aspiration (FNA) of the thyroid nodule, as this process is called, can usually be done quickly and inexpensively in a doctor’s office. However, because of limitations in the number of cells collected and the difficulty involved in making a thyroid cancer diagnosis, these tests aren’t always diagnostic.


Norman, J. (2009). Fine needle biopsy of thyroid nodules. Retrieved March 17, 2010, from the EndocrineWeb Web site:

Drucker, D. (2010). Diagnosis. Retrieved March 17, 2010, from the My Web site:

American Cancer Society staff. (2009). Detailed guide: Thyroid cancer, how is thyroid cancer diagnosed? Retrieved March 17, 2010, from the American Cancer Society Web site:

Mayo clinic staff. (2009). Tests and diagnosis. Retrieved March 17, 2010, from the Mayo Clinic Web site: