What actually happens when a patient receives a dose of radioactive iodine?

A certain amount of preparation is required before a patient receives a dose of radioactive iodine. If the patient has been taking an antithyroid drug for the treatment of hyperthyroidism, doses of the antithyroid drug must be held at least 3-4 days before the dose is administered. Women of childbearing age must have a urine test or blood test performed to rule out pregnancy before receiving a dose of radioactive iodine.

If a patient is being treated as an outpatient, the procedure is fairly straightforward. 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 amount of radioactivity in the dose has been confirmed, the patient is given the capsule to swallow. The patient may be instructed to drink a full glass of water after swallowing the capsule to ensure that it passes all the way into the stomach. After successful administration of the dose has been confirmed, the patient is usually able to go home with a list of precautions to be followed in order to avoid exposing others to the radiation released from 131-Iodine as it is cleared from the body.

If a patient is being treated as an inpatient, the procedure may be more involved. The administration of radioactive iodine therapy in a hospital usually involves preparation of a special isolation room that is shielded to contain the radiation released from 131-Iodine. An isolation room may have 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 that is later removed and discarded when the treatment is completed. Prior to administration, the amount of radioactivity in the dose is measured with a sensitive instrument. After the amount of radioactivity in the dose has been confirmed, the patient is given the capsule to swallow. The patient may be instructed to drink a full glass of water after swallowing the capsule to ensure that it passes all the way into the stomach. After successful administration of the dose has been confirmed, the patient may be placed in strict isolation. Visitors are not allowed, and special procedures must be followed whenever hospital 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 usually kept in strict isolation until the amount of radioactive energy that can be measured has fallen below a certain limit. This may occur overnight, or may take a day or two, depending on the dose that has been administered. Once this limit is reached, the patient is able to go home with a list of precautions to be followed in order to avoid exposing others to the radiation released from 131-Iodine as it is cleared from the body.