Radioactive Iodine Treatment
Pronounced: RAY-dee-oh-AK-tiv I-oh-dine
by Diana Kohnle
Radioactive iodine treatment is used to treat certain thyroid diseases. The procedure uses a radioactive form of iodine. Iodine is normally taken up by the thyroid gland. This radioactive iodine destroys cells in the thyroid. The radioactivity will have little affect on other parts of the body.
Reasons for Procedure
Radioactive iodine may be done to treat:
Radioactive iodine therapy may cause:
The procedure may be harmful to a fetus. It is not recommended for pregnant women. Nursing mothers should stop breastfeeding for at least a week after the procedure.
What to Expect
Prior to Procedure
Preparation for the surgery may include:
A pregnancy test will be done in women of childbearing age.
Description of the Procedure
The doctor will give radioactive iodine as pills or liquids. The thyroid will naturally absorb the iodine. It will pass out of the body through the urine.
How Long Will It Take?
At least an hour
Will It Hurt?
The treatment is painless.
The body can give off radiation for a few days. It can effect health of others that are nearby. A few days stay in the hospital may be needed. Other care will be needed at home including keeping distance from others.
Thyroid levels return to normal within 8 to 12 weeks for most who have treatment for hyperthyroidism. A second dose of radioactive iodine treatment is needed for some.
Radioactive iodine treatment can cause hypothyroidism (low thyroid hormones). It may be temporary or permanent. Thyroid levels will be checked every few months until levels are stable.
Call Your Doctor
Call your doctor if any of these occur:
If you think you have an emergency, call for emergency medical services right away.
American Thyroid Association
Hormone Health Network—Endocrine Society
Thyroid Foundation of Canada
Pluijmen MJ, Eustatia-Rutten C, Goslings BM, et al. Effects of low-iodide diet on postsurgical radioiodide ablation therapy in patients with differentiated thyroid carcinoma. Clin Endocrinol (Oxf). 2003;58(4):428-435.
Radioactive Iodine (Radioiodine) Therapy for Thyroid Cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/thyroid-cancer/treating/radioactive-iodine.html. Updated March 14, 2019. Accessed March 18, 2020.
Radioactive iodine for hyperthyroidism. Endocrine Society Hormone Health Network website. Available at:
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Accessed March 18, 2020.
Radioiodine (I-131) therapy. Radiological Society of North America Radiology Info website. Available at:
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Updated March 17, 2016. Accessed March 18, 2020.
Rivkees SA, Dinauer C. An optimal treatment for pediatric Graves’ disease is radioiodine. J Clin Endocrinol Metab. 2007;92(3):797-800.
Last reviewed November 2019 by EBSCO Medical Review Board James Cornell, MD
Last Updated: 3/18/2020
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