What actually happens when a patient receives radioactive iodine?

In the United States, regulations differ from state to state regarding the amount of radioactive iodine a patient can be given in various settings. Most of the differences concern the amount of radioactive iodine given on an outpatient basis. When the amount rises above a certain level, a patient must be hospitalized in shielded inpatient facilities. This limits the risks associated with exposing others to radiation.

A patient undergoes special preparation before receiving a dose of radioactive iodine. In order to maximize uptake of 131-Iodine by thyroid cancer cells, the patient has to experience thyroid hormone withdrawal. This process, which involves scheduled manipulation of doses of thyroid hormone, usually takes at least four weeks to complete. During this time the patient is also instructed to follow a special low-iodine diet that limits intake of certain foods. Women of childbearing age must have a pregnancy test performed and be confirmed negative before they receive any dose of 131-Iodine.

If a patient is being treated as an outpatient, the procedure is fairly straightforward. In order to reduce any possible nausea induced by the radioactive iodine, the patient may be given a dose of an antinausea medication prior to receiving 131-Iodine. The treatment dose of 131-Iodine is administered as a capsule that requires special shielding and handling. Prior to administration, the amount of radioactivity in the dose is measured with a sensitive instrument. After the dose has been confirmed, the patient swallows the capsule. It is important to make sure that the capsule passes all the way into the stomach to ensure delivery of the complete dose. After this has been confirmed, the patient is able to go home with certain precautions to be followed in order to avoid exposing others to radioactive iodine as it is cleared from the body.

If a patient is being treated as an inpatient, the procedure is more involved. Hospitalization to receive radioactive iodine therapy usually involves preparation of a special isolation room that is shielded to contain the energy released from 131-Iodine. An isolation room may have adequate shielding materials built into the walls. If not, special screens may be brought in to surround the patient during the treatment. Prior to treatment, the furnishings in an isolation room are usually wrapped in plastic, which is removed and discarded when the treatment is completed. In order to reduce any possible nausea induced by the radioactive iodine, the patient may be given a dose of an antinausea medication prior to receiving 131-Iodine. In order to reduce any possible irritation of the salivary glands, the patient may be instructed to suck on candy during the treatment to stimulate the flow of saliva. The treatment dose of 131-Iodine is administered as a capsule that requires special shielding and handling. Prior to administration, the amount of radioactivity in the dose is measured with a sensitive instrument. After the dose has been confirmed, the patient swallows the capsule. It is important to make sure that the capsule passes all the way into the stomach to ensure delivery of the complete dose. After this has been confirmed, the patient is placed in strict isolation. Visitors are not allowed, and special procedures must be followed whenever staff open the door or enter the room. At periodic intervals, an instrument is used to measure the amount of radioactive energy in the patient's body. This declines as the 131-Iodine is cleared from the body through the kidneys, passing out in the urine. The patient is kept in strict isolation until the amount of radioactive energy that can be measured has fallen to below a certain limit. This may occur overnight, or may take upwards of a few days, depending on the dose given. After this has been confirmed, the patient is able to go home with certain precautions to be followed in order to avoid exposing others to radioactive iodine as it is cleared from the body

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