Long-term Monitoring

There are three main tests that doctors may use after initial treatment to determine whether any thyroid cancer cells remain in the body: thyroglobulin (Tg) testing, neck ultrasound (US) and whole body scans (WBS).1  These tests are used long-term, on a schedule agreed with your doctor, to monitor for any new cancer cells.

Up to 30% of well-differentiated thyroid cancer patients may experience a recurrence, which is defined as the return of cancer after treatment and after a period of time during which the cancer cannot be detected.2

About 80% of those recurrences occur within 10 years of initial treatment, but can also take place decades later.3 The prognosis, or outlook, for thyroid cancer that has returned is improved when the recurrence is discovered early. This is why your doctor may recommend routine checkups for the rest of your life.

Tg Testing

Tg is a protein produced by thyroid cells (both normal and cancerous cells) and after thyroid ablation, it can be used as a cancer marker. After your surgery and radioiodine ablation, it may take months or years for Tg to reach this very low level.  A positive Tg test indicates that thyroid cells, either normal or cancerous, are still present in your body. Depending on the Tg results, your doctor may monitor you more closely with other tests or scans and may recommend additional treatment.4

Neck Ultrasound

Ultrasound test is a device that uses sound or other vibrations to image structures in the neck.  Radiologists use this technology to find potential disease by evaluating images of the thyroid.  It involves moving an instrument along your neck, without exposure to radiation.4  This procedure can help to identify cancerous growths, including location, blood flow, etc., for a physician to evaluate.5  A preoperative neck ultrasound for cervical lymph nodes is recommended by the American Thyroid Association for all patients undergoing thyroidectomy.1  This is the same ultrasound technology commonly used to image a fetus during pregnancy.

Ultrasound showing a nodular tumor in the thyroid gland

Copyright ©2016 Photo Researchers, Inc.

Radioiodine Whole Body Scan

This is typically a TSH-stimulated whole-body scan.  TSH stimulation can be accomplished by thyroid hormone withdrawal (i.e., you stop taking your thyroxine pills for a period of time) or after receiving a prescription medication from your healthcare provider.  

After TSH levels are increased, a low dose of radioactive iodine is given by mouth, usually in a pill. Elevated TSH levels are required to stimulate the uptake of radioactive iodine into remaining thyroid cells. After receiving the dose, a scan is performed to show where the iodine has collected in the body. It is normal for the salivary glands, gastrointestinal tract, and urinary tract/bladder to collect some of the radioactive iodine. Normal uptake may also be seen in the liver. After a dose of radioactive iodine, these areas may "light up" on scan; however, this does not mean that thyroid cancer has spread to these organs. Your care team will review the scans to determine if any thyroid tissue remains in your body.6


  1. Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2015; doi: 10.1089/thy.2015.0020.
  2. American Cancer Society. What is Cancer Recurrence?  2015. http://www.cancer.org/treatment/survivorshipduringandaftertreatment/understanding recurrence/whenyourcancercomesback/when-cancer-comes-back-what-is-recurrence. Accessed Dec 11, 2015.
  3. Mazzaferri EL, Jhiang SM. Long-term impact of initial surgical and medical therapy on papillary and follicular thyroid cancer. Am J Med. 1994;97:418-428.
  4. Thyroid Nodule Ultrasound. Endocrineweb. 2015.http://www.endocrineweb.com/conditions/thyroid/thyroid-nodule-ultrasound. Accessed December 14, 2015.
  5. American Association of Endocrine Surgeons. Thyroid cancer: Radioactive iodine (RAI or I131) treatment. 2015. http://endocrinediseases.org/thyroid/cancer_rai.shtml. Accessed Nov 4, 2015.
  6. ThyCa. Follow-up testing. 2013. http://www.thyca.org/pap-fol/follow-up-testing/. Accessed Oct 30, 2015.

Patient Organizations
Several organizations offer support and resources for thyroid cancer patients. Some of those are listed below for your reference.


Thyrogen® (thyrotropin alfa for injection) 0.9 mg/mL after reconstitution


There have been reports of events that led to death in patients who not had surgery to have their thyroid gland removed, and in patients with thyroid cancer cells that have spread to other parts of the body.

Patients over 65 years old with large amounts of leftover thyroid tissue after surgery, or with a history of heart disease, should discuss with their physicians the risks and benefits of Thyrogen.

Thyrogen can be administered in the hospital for patients at risk for complications from Thyrogen administration.

Since Thyrogen was first approved for use, there have been reports of central nervous system problems such as stroke in young women who have a higher chance of having a stroke, and weakness on one side of the body.

Patients should remain hydrated prior to treatment with Thyrogen.

Leftover thyroid tissue after surgery and cancer cells that have spread to other parts of the body can quickly grow and become painful after Thyrogen administration.

Patients with cancer cells near their windpipe, in their central nervous system, or in their lungs may need treatment with a glucocorticoid (a medication to help prevent an increase in the size of the cancer cells before using Thyrogen.)


In clinical studies, the most common side effects reported were nausea and headache.


Pregnant patients: Thyrogen should be given to a pregnant woman only if the doctor thinks there is a clear need for it.

Breastfeeding patients: It is not known whether Thyrogen can appear in human milk. Breastfeeding women should discuss the benefits and risks of Thyrogen with their physician.

Children: Safety and effectiveness in young patients (under the age of 18) have not been established.

Elderly: Studies do not show a difference in the safety and effectiveness of Thyrogen between adult patients less than 65 years and those over 65 years of age.

Patients with kidney disease: Thyrogen exits the body much slower in dialysis patients and can lead to longer high TSH levels.


Thyrogen is used to help identify thyroid disease by testing the blood for a hormone called thyroglobulin in the follow up of patients with a certain type of thyroid cancer known as well differentiated thyroid cancer. It is used with or without a radiology test using a form of iodine.

Limitations of Use:

The effect of Thyrogen on long term thyroid cancer outcomes has not been determined.

When Thyrogen is used to help detect thyroid cancer, there is still a chance all or parts of the cancer could be missed.

Thyrogen is also used to help patients prepare for treatment with a form of iodine to remove leftover thyroid tissue in patients who have had surgery to take out the entire thyroid gland for patients with well differentiated thyroid cancer who do not have signs of thyroid cancer which has spread to other parts of the body.

Limitations of Use:

In a study of people being prepared for treatment with a form of iodine after thyroid surgery, results were similar between those who received Thyrogen and those who stopped taking their thyroid hormone. Researchers do not know if results would be similar over a longer period of time.

See full Prescribing Information for more details.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.