What is Radioactive Iodine Ablation?

After a total thyroidectomy, some patients may need another procedure to remove any leftover thyroid tissue. This is called radioactive iodine ablation. The thyroid remnant is any leftover thyroid tissue that the surgeon was not able to remove during the total thyroidectomy.

Who is Radioactive Iodine Ablation for?

Radioactive iodine ablation is not recommended for all patients. Your doctor may consider risk factors such as the risk of recurrence when discussing whether ablation is right for you.For patients who receive a hemi-thyroidectomy, radioactive iodine ablation is not necessary. Your doctor will discuss this with you.

How Does Radioactive Iodine Ablation Work?

Radioactive iodine ablation is performed by giving the patient a dose of radiation in the form of a capsule or liquid. This type of radiation is called radioactive iodine. The radioactive iodine targets and destroys any remaining thyroid tissue or cells that may be present in the body.2 These cells may be normal thyroid cells, cancerous thyroid cells, or both.

This procedure is usually done several weeks after the thyroidectomy.3 Your doctor will also order a radiology test called a whole-body scan as part of the procedure.

Preparation for Radioactive Iodine Ablation

For the procedure to work effectively, the patient needs to have a high level of thyroid stimulating hormone (TSH) in the body. TSH stimulates thyroid cells to take in radioactive iodine. If a patient has started thyroid hormone replacement therapy after surgery, doctors may stop the medication to allow the TSH levels to rise. This is referred to as thyroid hormone withdrawal.

Stopping thyroid hormone replacement may cause the patient to experience symptoms of hypothyroidism. As an alternative to thyroid hormone withdrawal, your doctor may use a prescription medication that increases TSH levels without stopping thyroid hormone replacement.1 To learn more about this option click here.

In patients who have undergone total removal of the thyroid

After total removal of the thyroid, the effective Radioactive Iodine (RAI) ablation of remaining thyroid tissue can only be achieved by increasing the level of thyroid stimulating hormone (TSH) in the body. This can be achieved by one of two methods:

  1. Increase the level of thyroid stimulating hormone (TSH) by temporarily discontinuing thyroid hormone treatment thus making the patient hypothyroid.
  2. Raise the level of thyroid stimulating hormone (TSH) by injecting the patient with Thyrogen (thyrotropin alfa for injection). This method allows patients to remain on thyroid hormone medication and not become hypothyroid.


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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. Haugen BR, Alexander EK, Bible K, et al. 2015 American Thyroid Association (ATA) Management Guidelines for Adult Patient with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2015; DOI: 10.1089/thy.2015.0020.
  2. Norman, J. Endocrinweb. Thyroid Cancer. 2015. Accessed January 2019.
  3. American Association of Endocrine Surgeons. Thyroid cancer: Radioactive iodine (RAI or I131) treatment. 2015. Accessed January 2019.