Radioactive Iodine: A Patient's Guide

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Radioactive iodine (RAI) treatment, also known as radioactive iodine ablation or radioiodine ablation, is commonly used for patients with Graves’ disease, hyperthyroidism, or goiter (an enlarged thyroid). RAI is also an option after thyroid surgery for some cases of thyroid cancer. Because the thyroid is the only gland that absorbs iodine, doctors can target it using RAI without affecting other glands and organs.


RAI Treatment

Doctors usually administer RAI orally, in pill form. The iodine is taken up by the thyroid gland, where it destroys (ablates) thyroid tissue. To help release the RAI and clear it out of your body through urine, your doctor will likely advise you to drink extra fluids.


RAI Precautions

After RAI, your doctor will recommend these precautions to protect other people from radiation exposure:. The length of time you need to follow precautions depends on the RAI dosage.

  • Sleep alone.
  • Avoid physical contact with pregnant women, children, and pets.
  • Stay a safe distance away from others.
  • Avoid public places, including hotels and public transit.
  • Do not prepare food for others.
  • Avoid flying. If you must, bring a doctor’s letter in case you trigger security alarms at airport radiation detectors.


Hygiene after RAI

Hygiene is important after RAI ablation to protect others from radiation exposure as you clear the iodine out of your system. Experts recommend the following:

  • Don’t share personal items such as bedding and towels.
  • Wash your clothes and dishes separately.
  • Reserve a bathroom for yourself.
  • Wipe the toilet after each use.
  • Wash your hands often.
  • Shower daily.


RAI side effects

While RAI does not typically have many side effects, you may experience: Several days of neck tenderness or soreness.

  • A metallic taste in your mouth.
  • A dry mouth.
  • A sore throat.
  • Mild nausea.

You may also develop swollen salivary glands, which can last several weeks. Experts recommend sucking on sour candies to stimulate saliva flow.


RAI for hyperthyroid patients

When RAI ablation is used to treat hyperthyroidism (an overactive thyroid), over time the thyroid becomes less able to produce hormone. The change can take up to six months. If your dose of RAI was insufficient, your doctor may recommend a repeat treatment. While your doctor will attempt to give you a dose that returns you to the reference range, the majority of people who have RAI treatment eventually become hypothyroid, requiring thyroid-hormone replacement medication.


RAI for thyroid cancer patients

When RAI is given to treat thyroid cancer, it is typically administered after you have had a thyroidectomy (thyroid surgery to remove the gland). The objective with RAI is to destroy any remaining thyroid tissue and prevent cancer recurrence. After thyroidectomy and RAI treatment, you will become hypothyroid almost immediately, requiring thyroid-hormone replacement medication — usually levothyroxine — for life.


RAI and pregnancy

Doctors never knowingly perform RAI ablation on pregnant women, as iodine can cross the placenta and concentrate in the fetal thyroid gland, causing hypothyroidism. If you are of childbearing age, your doctor may perform a pregnancy test before RAI ablation. It is not recommended that you become pregnant until six months after treatment. Also note that RAI may affect menstruation, with some women experiencing irregular periods for as long as a year after treatment.


RAI and breastfeeding

Doctors don’t perform RAI ablation on women who are breastfeeding because the iodine can reach the baby via breast milk. This can negatively affect your baby's thyroid gland and function. If a doctor recommends a nursing woman undergo RAI ablation, you will need to stop. You can, however, safely breastfeed future babies.


Secondary cancer risk after RAI

If you get RAI treatment for thyroid cancer, your risk of developing certain secondary cancers increases by 18 percent, including:

  • Cancer of the salivary glands
  • Leukemia
  • Kidney cancer

After RAI ablation, you should undergo periodic screening and monitoring for signs and symptoms of these secondary cancers.


RAI and male infertility

Men who receive higher doses of RAI or multiple RAI treatments for thyroid cancer can in some cases experience decreased sperm counts, resulting in temporary infertility. This can last for as long as two years. If you are planning to have children, talk to your doctor about sperm banking.