Thyroid Cancer Testing and Diagnosis

Thyroid cancer happens when cells in your thyroid gland start to grow in an abnormal way. Your thyroid is a small, butterfly-shaped gland that sits low in your neck. It controls your energy, metabolism and many daily body functions. 

Finding thyroid cancer early gives you the best chance for successful treatment. The expert team at Banner MD Anderson Cancer Center is here to guide you every step of the way. Learn more about how thyroid cancer is tested and diagnosed. 

Your health care provider may recommend testing if you have one more of these common symptoms:

• A lump or swelling in the front of your neck
• Trouble swallowing or breathing
• A hoarse voice that does not go away
• Pain in the neck or throat
• A cough that isn’t linked to a cold, allergies or illness

These symptoms do not mean you have cancer. Many thyroid nodules are benign (not cancer). Testing helps your provider understand what is happening so they can choose the best next steps. 

Learn more about symptoms and types of thyroid cancer.

How thyroid cancer is diagnosed

Your primary care provider may use several tests to check your thyroid. You may not need all of them. Your exam, symptoms and medical history help determine which tests are right for you.

Physical exam and medical history

Your visit often begins with a simple physical exam. Your provider will:

• Feel the front of your neck for lumps or swelling
• Check your lymph nodes 
• Ask about symptoms like voice changes or swallowing problems
• Review your family history, radiation exposure or other risks 

This exam helps guide what testing comes next.

Thyroid ultrasound

A high-resolution thyroid ultrasound is one of the first and most important tests. It uses sound waves to create clear pictures of your thyroid. 

What the ultrasound shows:

• The size and shape of the thyroid
• If nodules are solid or filled with fluid
• Features that may look suspicious
• Whether nearby lymph nodes look enlarged 

What to expect during the test:

• You lie on an exam table with your head tilted back
• Warm gel is placed on your neck
• A small wand (transducer) moves over your skin
• The test is painless and takes about 20 minutes

Radiologists use a rating system (like TI-RADS) to decide if a nodule needs a biopsy. 

Blood tests 

Blood tests cannot diagnose thyroid cancer. They check how well the thyroid is working and may support other test findings. 

Common blood tests include:

• TSH (thyroid-stimulating hormone): Shows if your thyroid is underactive or overactive
• T3 and T4: Measures thyroid hormone cells 
• Thyroglobulin: Used mostly after treatment to monitor certain cancers
• Calcitonin: Helps diagnose medullary thyroid cancer
• CEA (carcinoembryonic antigen): Another marker used for medullary thyroid cancer

Fine needle aspiration (FNA) biopsy

An FNA biopsy is the most common way to confirm or rule out thyroid cancer. It shows whether a thyroid nodule is benign or cancerous. 

How the biopsy works:

• Your skin is numbed with a small injection
• A thin needle is guided into the nodule with ultrasound
• A small sample of cells is removed
• The test takes only a few minutes
• Most people feel pressure but no pain

Understanding your biopsy results:

• Benign: No cancer found (nodules fall here)
• Malignant: Cancer cells are present
• Indeterminate: Not clearly benign or cancerous
• Non-diagnostic: Not enough cells collected 

If the results are indeterminate, your provider may suggest repeat testing, molecular testing or, in some cases, surgery.

Molecular testing

Molecular testing looks for specific gene mutations or patterns in the nodule. It helps:

• Predict whether a suspicious nodule is cancer
• Guide treatment options
• Support decisions about surgery, radioactive iodine therapy or surveillance (monitoring)

This test is most helpful when biopsy results are unclear.

Imaging tests

Your provider may use additional imaging if more information is needed.

• Computed tomography (CT) scan: A CT scan shows detailed pictures of your neck and chest. It helps check tumor size and whether the cancer has spread to the lymph nodes or the lungs.
• Magnetic resonance imaging (MRI): An MRI is useful for people who cannot receive contrast dye or when more detail is needed around the spine or windpipe. 
• Radioactive iodine scan: This scan is used mostly after the thyroid has been removed. It helps find cancer cells that absorb iodine.

How thyroid cancer is staged

Once a diagnosis is confirmed, your care team will determine the cancer’s stage. Staging shows whether the cancer is only in the thyroid or has spread. 

The most common system is the TNM system:

• T (tumor): The size of the tumor
• N (nodes): Whether it spread to lymph nodes 
• M (metastasis): Whether it spread to other organs

Specialists use stages 0 to 4 (0 to IV) to describe the cancer’s advancement. Your care team will explain your stage and what it means for treatment and recovery.

Should I consider genetic testing?

Genetic testing may be helpful if you have a strong family history of thyroid cancer or known hereditary conditions. These rare conditions raise the chance of thyroid cancer and may require early screening. 

Examples include:

• MEN2 (multiple endocrine neoplasia, type 2)
• Cowden syndrome
• Familial medullary thyroid cancer
• Familial adenomatous polyposis (FAP)
• DICER1 syndrome

A genetic counselor can help you understand your risks and decide if testing is right for you. 

Learn more about genetic counseling. 

What happens after diagnosis?

If tests confirm thyroid cancer, your care team will talk with you about:

• The type of cancer you have and what stage it is in
• Whether or not it has spread
• Recommended treatments (such as surgery, radioactive iodine or medications)
• What to expect during recovery
• Follow-up appointments and long-term monitoring

Most people do very well with treatment, especially when thyroid cancer is found early. 

Learn more about the treatment of thyroid cancer. 

Find a thyroid cancer specialist

The experts at Banner MD Anderson  are here to help with testing, diagnosis and treatment planning.  

Request an appointment