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Radioactive Iodine Treatment

What is Radioactive Iodine Treatment and How Does It Work?


Updated April 01, 2013

Radioactive iodine therapy (RAI) is a type of thyroid cancer treatment that utilizes radioactive iodine to destroy thyroid cells. The radioactive iodine, also called I-131, is considered to be an effective form of treatment and is often given after a thyroidectomy to eliminate any residual thyroid cancer cells that may be circulating the body. It is also used after a recurrence has been detected or if the cancer has spread. RAI is used exclusively in follicular and papillary thyroid cancer types.

How Does RAI Work?

The thyroid gland uses iodine from our water and food intake to produce essential hormones that regulate our metabolism. Thyroid cells are unique because they are the only cells in the body that absorb iodine. Before undergoing RAI treatment, patients go on a low-iodine diet, starving the body of iodine. When a patient is given radioactive iodine, the iodine starved thyroid cells uptake the RAI, and the cells are destroyed, or ablated.

Side Effects of RAI Therapy

Most people do not experience any side effects from radioactive iodine treatment. However, when someone does experience side effects from treatment, they are considered to be short term. Common side effects include taste changes, loss of taste, sore throat, salivary gland swelling, neck swelling, fatigue and nausea/vomiting. Dry mouth is another common side effect that can occur with RAI. Less commonly, the inability to produce tears can occur.

Although rare, radioactive iodine treatment can lower sperm count in men and may also cause infertility. Women may experience changes in their menstrual cycle for a few months after treatment. Women should not get pregnant for up to a year after having RAI, or as directed by their physician. Women who are breastfeeding should not breastfeed until given approval from their physician.

According to the American Cancer Society, those who undergo RAI may face an small, but increased risk for developing leukemia. Surgery is the first approach to treating papillary thyroid cancer by removing all or part of the thyroid gland. In most cases, the entire thyroid is removed during a procedure called a total thyroidectomy. By removing the entire thyroid, the chance of future recurrence is lower and follow-up treatment, such as radioactive iodine therapy, can be more effective.

Several surrounding lymph nodes may also be removed during surgery. Thyroid tissue and lymph nodes will be examined by a pathologist after the surgery to determine if the disease has spread, and if so, how far. This is called staging.

Those who have a total thyroidectomy as treatment for papillary thyroid cancer will require thyroid hormone replacement medication for the rest of their lives. Since the thyroid was removed during surgery, it can no longer produce the hormones needed to regulate metabolism and other critical functions. This thyroid hormone suppression therapy (THST) is available by pill and usually taken once a day. It also serves to suppress thyroid stimulating hormone in the body, which can reduce the risk of recurrence. (Read more about the function of the thyroid.)

After surgery, your doctor may recommend treatment called radioactive iodine (RAI) ablation. The goal of RAI ablation is to destroy any remaining thyroid cells in the body. This is accomplished by restricting the amount of iodine in the diet, ultimately starving residual thyroid cells of it. After a few weeks of following a special low-iodine diet, you will be given a pill containing radioactive iodine. The iodine-deprived thyroid cells will absorb the radioactive iodine and die. During RAI therapy, you may be hospitalized for a few days to reduce the risk of exposing others to radiation.

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