Radioactive Iodine Therapy
Radioactive iodine (I-131) therapy is a treatment for papillary or follicular thyroid cancer. It kills thyroid cancer cells and normal thyroid cells that remain in the body after surgery.
People with medullary thyroid cancer or anaplastic thyroid cancer usually do not receive I-131 therapy. These types of thyroid cancer rarely respond to I-131 therapy.
Even people who are allergic to iodine can take I-131 therapy safely. The therapy is given as a liquid or capsule that you swallow. I-131 goes into the bloodstream and travels to thyroid cancer cells throughout the body. When thyroid cancer cells take in enough I-131, they die.
Many people get I-131 therapy in a clinic or in the outpatient area of a hospital and can go home afterward. Some people have to stay in the hospital for one day or longer. Ask your health care team to explain how to protect family members and coworkers from being exposed to the radiation.
Most radiation from I-131 is gone in about one week. Within three weeks, only traces of I-131 remain in the body.
During treatment, you can help protect your bladder and other healthy tissues by drinking a lot of fluids. Drinking fluids helps I-131 pass out of the body faster.
Some people have mild nausea the first day of I-131 therapy. A few people have swelling and pain in the neck where thyroid cells remain. If thyroid cancer cells have spread outside the neck, those areas may be painful too.
You may have a dry mouth or lose your sense of taste or smell for a short time after I-131 therapy. Chewing sugar-free gum or sucking on sugar-free hard candy may help.
A rare side effect in men who receive a high dose of I-131 is loss of fertility. In women, I-131 may not cause loss of fertility, but some doctors advise women to avoid getting pregnant for one year after a high dose of I-131.
Researchers have reported that a very small number of patients may develop a second cancer years after treatment with a high dose of I-131. See the "Follow-up Care" section for information about checkups after treatment.
A high dose of I-131 also kills normal thyroid cells, which make thyroid hormone. After radioactive iodine therapy, you need to take thyroid hormone pills to replace the natural hormone.
You may want to ask your doctor these questions before having radioactive iodine therapy:
- Why do I need this treatment?
- What will it do?
- How do I prepare for this treatment? Do I need to avoid foods and medicines that have iodine in them? For how long?
- Will I need to stay in the hospital for this treatment? If so, for how long?
- How do I protect my family members and others from the radiation? For how many days?
- Will the I-131 therapy cause side effects? What can I do about them?
- What is the chance that I will be given I-131 therapy again in the future?
