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Everything you need to know about Radioactive Iodine Therapy (RAI)

Everything you need to know about Radioactive Iodine Therapy (RAI)

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Medically reviewed by

Natalie Bessom, D.O. Board-certified family medicine doctor with specialty training in nutrition, USA

The name “Radioactive Iodine” can seem a little scary but it’s actually a common way to treat an overactive thyroid (hyperthyroidism) and thyroid cancer.

Radioactive Iodine Therapy (RAI) is a safe, normally well tolerated, and common treatment that targets the thyroid cells. 

This article will discuss:

  • What is Radioactive Iodine Therapy (RAI)? 
  • How does Radioactive Iodine Therapy (RAI) treat hyperthyroidism?
  • How does Radioactive Iodine Therapy (RAI) treat thyroid cancer?
  • What are the side effects of Radioactive Iodine Therapy (RAI)?
  • What are the special concerns for women and men?

What is Radioactive Iodine Therapy (RAI)?

Radioactive Iodine Therapy (RAI) is given as a pill or liquid form to treat hyperthyroidism and thyroid cancer. 

Iodine is made in 2 radioactive forms that are used to treat those with a thyroid condition: 

How does Radioactive Iodine Therapy (RAI) treat hyperthyroidism?

Hyperthyroidism is where the body has an overactive thyroid and produces too much thyroid hormone. When there is too much thyroid hormone, every function in the body essentially speeds up. 

Symptoms of hyperthyroidism include: 

  • Rapid heart rate
  • Nervousness and anxiety 
  • Irritability 
  • Increased sweating 
  • Difficulty sleeping 

Because the thyroid gland uses iodine to make these hormones, RAI treats hyperthyroidism by damaging or destroying all the thyroid cells or by shrinking the thyroid glands that are causing problems due to their size, also known as a Goiter. 

According to the American Thyroid Association, the end result of RAI treatment of hyperthyroidism is hypothyroidism (underactive thyroid), which is treated by thyroid hormone replacement.

How does Radioactive Iodine Therapy treat thyroid cancer?

The most common types of thyroid cancer (papillary and follicular) are often treated with large doses of I-131 that aim to destroy thyroid cancer cells. 

The dosage for treating thyroid cancer is much higher than treating those with hyperthyroidism. This therapy is usually given after the removal of the thyroid gland (thyroidectomy) to destroy any remaining cancerous tissue. 

The thyroid gland collects and absorbs the majority of iodine in the body. When it is removed, there may still be some cells left and those remaining cells will continue to latch onto iodine. 

Before treatment, patients do not consume any salt so that these cells are deprived of iodine. When RAI is given, those lingering cells will absorb the iodine and be destroyed. 

Radioactive iodine therapy cannot be used to treat anaplastic (undifferentiated) and medullary thyroid carcinomas because these types of cancer do not absorb iodine.

What are the side effects of Radioactive Iodine Therapy (RAI)?

As mentioned above, hypothyroidism is an expected side effect of RAI treatment for hyperthyroidism. 

Some other temporary side effects of RAI include: 

  • Neck tenderness and swelling
  • Nausea
  • Loss or change of taste
  • Dry mouth/ insufficient saliva production
  • Dry eyes 

When undergoing RAI, your body will give off radiation for a period of time of a few days after the therapy. Depending on the dose of radioiodine administered during treatment, you may be required to stay in a specially isolated room in the hospital to prevent others from being exposed to radiation. Your healthcare provider will determine what is the appropriate time length. 

Your healthcare provider will provide specific instructions afterwards on how to prevent radioactive exposure to others. The length of time you need to follow these instructions and safety measures will depend on the strength of your dose of RAI.

Precautions may include: 

  • Avoiding prolonged physical contact especially children and pregnant women
  • Avoiding public places or try to maintain a safe distance from others
  • Avoiding sharing cooking utensils, bedding, towels, and personal items with others

What are the unique concerns for women and men with RAI?

According to the American Cancer Society, men who receive large total doses of radiation because of repeat RAI treatment may have lower sperm counts or, rarely, become infertile.

Women who undergo RAI treatment should never be pregnant or nursing. This protects the baby from receiving radioactive milk. The American Thyroid Association recommends that breastfeeding must be stopped at least 6 weeks before administration of I-131 treatment and should not be restarted after administration of RAI, but can be safely done for future pregnancies.

Furthermore, any attempts to conceive should be put off for at least 6 – 12 months after RAI. This ensures that the ovaries have adequate time free of radiation exposure and for thyroid hormone levels to return to normal and become stable before pregnancy. 

Radioactive iodine may also affect a woman’s ovaries, and some women may have irregular periods (spotting/inconsistency) for up to a year after treatment.

Key Takeaways

  • Radioactive Iodine Therapy (RAI) common way to treat an overactive thyroid (hyperthyroidism) and thyroid cancer
  • Radioactive Iodine Therapy (RAI) is given as a pill or liquid form to treat hyperthyroidism and thyroid cancer
  • Iodine is made in 2 radioactive forms that are used to treat those with a thyroid condition: 
    • I-123 (harmless to thyroid cells)
    • I-131 (destroys thyroid cells)
  • RAI treats hyperthyroidism by damaging or destroying all the thyroid cells or to shrink the thyroid glands that are causing problems due to their size
  • The end result of RAI treatment of hyperthyroidism is hypothyroidism (underactive thyroid), which is treated by thyroid hormone replacement
  • Thyroid cancer (papillary and follicular) are often treated with large doses of I-131 and used to destroy thyroid cancer cell
  • Side effects of RAI include:
    • Neck tenderness and swelling
    • Nausea
    • Loss or change of taste
    • Dry mouth/ insufficient saliva production
    • Dry eyes 
  • After receiving RAI, you may be required to stay in a specially isolated room in the hospital to prevent others from being exposed to radiation
  • Men who receive large total doses of radiation because of many treatments with RAI may have lower sperm counts or, rarely, become infertil
  • Women who are pregnant or breastfeeding should not undergo RAI to prevent the baby from being exposed to radiation and drinking radioactive milk

Undergoing treatment for thyroid cancer can be difficult to understand and manage. ThyForLife was built by a thyroid cancer survivor after her own battle. 

The ThyForLife app can help you easily manage the different aspects of your thyroid health journey from bloodwork, medication, supplements, symptoms and more – so you can get back to focusing on what matters. 

At ThyForLife, we do our utmost to provide accurate information. If you require more detailed information regarding medical terms, conditions, and practices please consult your healthcare professional. Always listen to the advice of your healthcare provider.

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