Radioactive Iodine Therapy

Radioactive iodine I-131 treatment is a nuclear medicine treatment, and it is also called Radioiodine I-131. This treatment is used to treat an overactive thyroid gland called hyperthyroidism. Hyperthyroidism can result from Graves’ disease, where the entire thyroid gland is overworked, or from nodules within the gland that produce too much thyroid hormone locally.

Radioactive Iodine Therapy

Nuclear medicine uses a small amount of radioactive material called a radiotracer. Doctors use nuclear medicine to diagnose, evaluate, and treat a variety of diseases. These include cancer, heart disease and gastrointestinal, endocrine, neurological disorders and other medical conditions. Nuclear medicine exams identify molecular activities. This gives them the ability to find diseases in their early stages. They can also show whether you are responding to treatment.

Things to Know Before Radioactive Iodine Treatment

You should not eat or drink anything after midnight the day before the procedure. If you are taking anti-thyroid medications, you should stop taking them at least three days before the treatment. Your doctor will usually recommend discontinuing the thyroid medication five to seven days before treatment.

You will be able to return home after radioactive iodine treatment. However, you should avoid prolonged and close contact for several days with other people, especially pregnant women and young children. Most of the unabsorbed radioactive iodine leaves the body during the first two days after treatment, mainly through urine. Small amounts may also be excreted through saliva, sweat, tears, vaginal secretions and faeces.

If your job or daily activities involve prolonged contact with young children or pregnant women, you should wait a few days after treatment to resume these activities. Patients with children at home should arrange for someone else to care for their child for the first few days after treatment. Your radiologist can be more specific about your particular situation, but it's usually between two and five days.

How is Radioactive Iodine Treatment Applied?

Treatment of hyperthyroidism is almost always carried out on an outpatient basis, as the required dose is relatively small.

Radioactive iodine I-131 is swallowed in a single capsule or liquid dose and is rapidly absorbed from the gastrointestinal (GI) tract into the bloodstream. It concentrates from the blood in the thyroid gland, where it begins to destroy the cells of the gland. Although the radioactivity remains in the thyroid gland for a while, it decreases significantly in the first few days. It usually takes one to three months for the effect of this treatment on the thyroid gland to take effect. Maximum benefit occurs three to six months after treatment. Hypothyroidism can usually be successfully treated with a single dose.