RAI is the most commonly performed treatment for resolving cases of severe hyperthyroidism. Most people with Graves’ disease, the most common cause of an overactive thyroid, are recommended for this procedure if medications fail to sufficiently slow-down an over-producing gland.
Patients with papillary or follicular thyroid cancer may also be referred for this procedure, following surgical removal of their glands (total thyroidectomy), to eradicate any remaining thyroid cells that can potentially contain malignancy.
How Does RAI Work?
The goal of RAI includes the following desired results:
- to destroy and eradicate all thyroid tissue and/or malignant cells in the body
- to stop the natural thyroid hormone production in the gland
- to correct hyperthyroidism
- to restore normal metabolism to the body
Once a dose of radioactive iodine that is large enough to completely kill the cells in a thyroid gland has been administered, the iodine is immediately absorbed by the gland. It does this because the thyroid is dependent on iodine to manufacture thyroid hormone. Once iodine enters the body through a person’s diet or by oral dosing, the gland absorbs it to regulate bodily metabolism via these hormones.
An overactive thyroid gland will absorb more iodine than a normal-functioning gland will. Patients scheduled for RAI are placed on a “no iodine diet” for two weeks or more previous to the procedure, so that the thyroid gland absorbs the radioactive iodine as completely as possible.
What is the Result?
The radioactivity in the iodine enters the cells of the gland and causes them to die. The goal of the treatment is to fully eradicate all thyroid tissue from the body, so that it ceases to produce thyroid hormone. This will correct the hyperthyroidism.
Once thyroid hormone levels begin falling to lower levels following RAI, the overactive bodily metabolism slows down from the hyperthyroid state. Several weeks following the procedure the patient’s thyroid hormone levels will fall to hypothyroid levels (under-active). The resulting hypothyroidism must then be treated (usually lifelong) with thyroid hormone replacement therapy to raise bodily metabolism back to a normal level.
What are the Risks?
RAI is a safe and effective procedure in most cases; there are, however, some medical sources that state that the treatment places some patients at risk for a worsening of thyroid eye disease (inflammatory condition in the eyeballs).
Other side effects that are temporary may include the following:
- sore throat
- dry mouth
- mild nausea
- dizziness
- fatigue
Some patients will rarely also see thyroid tissue that is not fully eradicated from the body that regrows and becomes revitalized and begins producing thyroid hormone. If it does so at an abnormally high level as it did before the procedure, this may require that the treatment be re-administered.
Patients are also required to be quarantined from family and pets for five to seven days due to risk of exposing them to radiation that remains in the body for a period following the procedure and can be spread by close contact.
Some thyroid-treating doctors offer a choice between thyroidectomy and RAI procedures to some of patients in need of thyroid ablation/removal (depending on individual cases). Patients should become educated about both options and fully discuss them with their treating doctor so that they feel comfortable and confident about the procedure they choose to have their doctors perform.
Sources:
Thyroid Cancer Survivors' Association
Diabetes and Hormone Center of the Pacific
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