Thyroid Cancer Diagnosis - Procedures and Tests

Female doctor examining male patient's glands in clinic
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How is thyroid cancer typically diagnosed? Comprehensive and thorough diagnosis of thyroid cancer involves a number of procedures and tests.

Triggers

Commonly, the process of evaluating for thyroid cancer starts with a lump or nodule in the gland. You may find it yourself, or be able to see it. In some cases, your doctor may detect it when handing your neck. It's also fairly common for thyroid nodules to be discovered when you have x-rays of the head or neck.

There are even cases of hairdressers noticing thyroid nodules. 

You can do a home test to help detect nodules. The "Thyroid Neck Check" is not conclusive, and does not rule out the possibility that you have a nodule, but if nodules are closer to the surface or large, the may be detected with this simple test. 

Physical Exam

Your doctor should conduct a thorough physical exam. This exam should include palpation of your thyroid, where the doctor physically feels for enlargement and lumps in your thyroid gland, and assesses the gland's size, and asymmetry, and the firmness. The doctor will also look for any enlarged lymph nodes in your neck and area around the gland.

Keep in mind that thyroid nodules are very common. Most, however, are benign. According to the American Cancer Society, less than 1 in 10 thyroid nodules are cancerous. 

You can find out more details about the other important assessments in this article on what goes in to a thorough clinical examination of the thyroid.

Biopsy

Doctors often biopsy suspicious thyroid nodules, to evaluate for potential cancer. Typically thyroid nodules are biopsied using a needle, in a procedure known as "fine needle aspiration biopsy" -- sometimes abbreviated FNA. Some patients have a surgical biopsy, where the nodule, or the thyroid gland itself, is removed surgically.

In some cases, the biopsy is "ultrasound-guided" so that the nodule can be more accurately sampled by the physician or pathologist performing the biopsy. 

You can read this Q&A on Fine Needle Aspiration Biopsy of the Thyroid for more detailed information on the FNA biopsy procedure.

Note: A new test available since 2011, called the Veracyte Afirma Thyroid Analysis, eliminates indeterminate or inconclusive thyroid nodule biopsy results.

Imaging Tests

A variety of imaging tests and scans are used to evaluate thyroid nodules for possible thyroid cancer. These include:

  • Nuclear scan, also known as radioactive iodine uptake (RAI-U) scan. In this test, you are given a radioactive tracer dose, followed by the scan. Nodules that absorb more radioactive iodine, and therefore are more visible, show up on the scan. These are known as "hot nodules" and are more likely to be benign.
  • CT scan, known as computed tomography or a "cat scan," is a specialized type of x-ray that is sometimes used to evaluate the thyroid. A CT scan can't detect smaller nodules, but may help detect and diagnose a goiter, or larger thyroid nodules.
  • Magnetic resonance imaging (MRI), can help detect enlargement in your thyroid gland, as well as tumors, and tumor size. MRI can also be helpful in detecting the spread of tumors. 
  • Thyroid ultrasound can tell whether a nodule is a fluid-filled cyst or a mass of solid tissue, but it cannot determine if a nodule or lump is malignant.

More information on imaging tests for the thyroid is included in this article on Thyroid Imaging Tests.

Blood Tests

Blood tests cannot diagnose thyroid cancer itself, or detect a cancerous thyroid nodule. Thyroid stimulating hormone (TSH) blood tests, however, may be used to evaluate the thyroid's activity and test for hypothyroidism or hyperthyroidism.

When medullary thyroid cancer is suspected, doctors will typically test for high levels of calcium, as this can be an indicator. They may also do genetic testing to identify the abnormal gene associated with some cases of medullary thyroid cancer.

Laryngosocopy

Less commonly, if a thyroid lump is close to your voice box, known as the larynx, a laryngoscopy will be performed. This test involves inserting a lighted flexible tube to view your larynx at high magnification. 

More Information on Thyroid Cancer

Find out more about the risk factors for thyroid cancer, and the signs and symptoms of thyroid cancer.

Sources:

Braverman, MD, Lewis E., and Robert D. Utiger, MD. Werner and Ingbar's The Thyroid: A Fundamental and Clinical Text. 9th ed., Philadelphia: Lippincott Williams & Wilkins (LWW), 2005.

National Cancer Institute -- Thyroid Cancer Page

What You Need to Know About Thyroid Cancer, National Cancer Institute

American Cancer Society: Thyroid Cancer Guide

Thyroid Cancer Survivors Association (ThyCa)

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