Radioactive Iodine Treatment

Diseases and Conditions · Hyperthyroidism · Hypothyroidism · Thyroid Cancer · Hashimoto’s Thyroiditis Treatments · Radioactive Iodine Treatment · Thyroid Hormone Treatment · Thyroid Surgery Our Staff

If you have an overactive thyroid gland or have been diagnosed with thyroid cancer, your endocrinologist may prescribe radioactive iodine (radioiodine) as part of your overall treatment.

The thyroid gland produces hormones that regulate the body’s metabolism. In order to produce these hormones, the thyroid gland requires large amounts of iodine, which is found in seafood, table salt, bread, and various other foods. Iodine is an essential ingredient in the creation of thyroid hormone. Each molecule of thyroid hormone contains either 4 (T4) or 3 (T3) molecules of iodine. Most overactive thyroid glands are quite hungry for iodine, and it was discovered in the 1940s that the diseased thyroid could be “tricked” into destroying itself by simply feeding it radioactive iodine. Your endocrinologist can also use radioiodine to treat some types of thyroid cancer. Fortunately, the radioiodine treatment itself will not cause you to feel bad, and very little radiation exposure occurs to the rest of the body.

Radioiodine has been used for more than 50 years in the treatment of thyroid diseases with remarkably few undesirable effects. However, problems may rarely occur when very large doses are given, including decrease in taste sensation and irritation of the salivary glands, the gastrointestinal tract, or the urinary bladder. No increase has been seen in either the occurrence of malignant tumors in patients treated with radioiodine or the number of birth defects in children born later to women who have received this type of treatment.

Radioactive iodine is given by mouth, usually in capsule form, and is quickly absorbed from the bowel. It then enters the thyroid cells from the bloodstream and gradually destroys them. Although the radioactivity from this treatment is largely gone from the body within a few days, its effect on the thyroid gland usually takes between 1 and 3 months to develop, and maximal benefit is usually noted within 3 to 6 months.

It is not possible to reliably destroy part but not all of the diseased thyroid gland, since the effects of the radioiodine are slowly progressive on the thyroid cells. Therefore, most endocrinologists strive to completely destroy the diseased thyroid gland with a single dose of radioiodine. This results in the intentional development of an underactive thyroid state (hypothyroidism) which is easily, predictably and inexpensively corrected by lifelong daily use of oral thyroid hormone replacement therapy.