Why do I Need Ongoing Monitoring?

After total thyroidectomy, up to 30% of well-differentiated thyroid cancer patients may experience a recurrence. This is defined as the return of cancer after treatment and after a period of time during which the cancer cannot be detected.1

About 80% of those recurrences happen within 10 years of initial treatment. But recurrences can also take place decades later.2 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.

What Tests will my Doctor Perform?

There are tests that doctors may use after initial treatment to determine the success of the treatment and whether any thyroid cancer cells remain in the body:

  • thyroglobulin (Tg) testing,
  • Stimulated thyroglobulin (StimTg) testing,
  • Post Op Stim (Tg) testing,
  • neck ultrasound (US), and
  • whole body scans (WBS).3
  • thyroid hormone levels
  • other imaging studies

These tests are used long-term, on a schedule agreed with your doctor, to monitor for any new cancer cells.

Tg blood Testing

Tg is a protein produced by both normal and cancerous thyroid cells. After thyroid ablation, it can be used as a cancer marker. 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

Stim Tg Testing

The sensitivity of the Tg blood test can be enhanced by stimulating the body prior to the blood test with high levels of thyroid stimulating hormone (TSH). TSH stimulates thyroid cells to release thyroglobulin into the blood. TSH can be increased by stopping the thyroid replacement medication in preparation for the blood test.

Stopping the thyroid hormone medication may cause the patient to experience symptoms of hypothyroidism. As an alternative, your doctor may use Thyrogen, which increases TSH levels without stopping thyroid hormone replacement.3

Studies show that the highest degrees of sensitivity for serum Tg to detect thyroid cancer are noted following stimulation.1

Neck Ultrasound

An ultrasound is a device that uses sound or other vibrations to create images of structures in the body. Radiologists use neck ultrasounds to check for any recurrence of thyroid cancer. The procedure can help to identify cancerous growths, including location, blood flow, etc., for a physician to evaluate.4

Radioiodine Whole Body Scan

A whole-body scan is performed as part of a radioactive iodine ablation procedure. It helps your doctors determine if any thyroid tissue remains in your body after initial surgery.5

The scan works as follows:

  • A low dose of radioactive iodine is given by mouth, in the form of a capsule or liquid
  • The radiation is taken in by any thyroid cells remaining in your body
  • After receiving the dose, a scan is performed to show where the iodine has collected in the body. These areas may "light up" on the scan.
  • Your care team will review the scans to determine if any thyroid tissue remains in your body.6


Thyroid Cancer Glossary

Low-Iodine Diet

My Doctor Discussion Guide

My Doctor Discussion Guide

More Resources

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


Diagnostic: 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.

Ablation: 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.


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.

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


  1. ThyCa. Facts About Thyroid Cancer. 2016. Accessed January 2019.
  2. 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.
  3. 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.
  4. Thyroid Nodule Ultrasound. Endocrineweb. 2015. Accessed January 2019.
  5. ThyCa. Follow-up testing. 2013. Accessed January 2019.
  6. American Association of Endocrine Surgeons. Thyroid cancer: Radioactive iodine (RAI or I131) treatment. 2015. Accessed January 2019.