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Pharmacy and Medications

RADIOACTIVE IODINE

10/30/2001

Question:

I AM SCHEDULED TO TAKE RADIOACTIVE IODINE FOR HYPERTHYROIDISM ON 7/25. INFO ON THIS IS LIMITED & I HAVE A FEW QUESTIONS: I WAS TOLD THAT I SHOULD AVOID TOUCHING ETC OTHER INDIVIDUALS...WHAT WILL HAPPEN TO THEM SHOULD THIS OCCUR - I AM PARTICULARLY CONCERNED ABOUT MY MOM WHO IS 78? HOW LONG DOES THIS TAKE TO LEAVE THE BODY? AM I IN ANY PHYSICAL DANGER FROM THIS MEDICATION? WHAT SHOULD I DO OR NOT DO PRIOR TO THIS EVENT? THANKS FOR ANY INFO YOU CAN PROVIDE.

Answer:

Although this response is not as timely as I would have liked, I hope the following is still helpful. The thyroid gland, located in the neck, produces several hormones that regulate growth, digestion and metabolism. Hyperthyroidism results from overstimulation of the thyroid gland to release these hormones. The result, then, is a group of symptoms including (but not limited to) weight loss, increased appetite, intolerance to heat, restlessness/nervousness, frequent bowel movements, and muscle cramps/fatigue. Hyperthyroidism can be caused by Graves` disease (85% of cases), certain types of tumors, inflammation of the thyroid and ingestion of excessive amounts of thyroid hormone or iodine. Laboratory tests conducted to help in the diagnosis of hyperthyroidism include thyroid stimulating hormone (TSH) levels, which would be abnormally low, and T3 and T4 levels, which would be abnormally high. Patients suffering from hyperthyroidism have several treatment options. Antithyroid medications, including methimazole (Tapazole) and propylthiouracil, work by slowing down the thyroid hormone and restoring normal levels. The disadvantage of using these as treatment is that they must be taken daily for 6-12 months, and 60-80% of patients who stop taking them at this point relapse. They also have some serious side effects in some patients. Surgery is another option, though it is usually reserved for patients who fail other treatments. The most popular treatment option for patients is radioactive iodine because it is 90% effective with one dose, it is virtually free of side effects, and it is the least expensive of all the options. Radioactive iodine is effective because the thyroid gland is naturally dependent on iodine to produce thyroid hormone. And so, when patients are given doses of radioactive iodine, the cells of the thyroid gland take it up into the gland (uptake) for use. Because the iodine is radioactive, this uptake results in the radiation and destruction of the cell; the more iodine given, the greater the number of cells that are affected. This radioactive iodine is quickly cleared, so it poses little danger to other cells of the body. Only the thyroid gland is affected and long-term studies show no increase in cancer mortality for patients who have received radioactive iodine therapy. After treatment, there is the possibility that your contacts may be adversely affected by your treatment. Radiation treatment targets an overactive thyroid gland and attempts to normalize its function. The quality of this treatment is such that it can be emitted to others, either through body fluids or close contact. This may affect close contacts such that they will also show decreased thyroid function. The risk is low, but precautions are taken to further minimize any risk to others. Generally, children and pregnant women are most at risk. Precautions taken for at least three days following treatment are recommended to allow time for the body to eliminate the radioactive iodine. These precautions include: 1. Avoiding close contact with any one person for longer than two hours in any 24-hour period of time. 2. Avoiding close contact with others that may result in them being near the neck (radioactive iodine is concentrated in the thyroid gland, in the neck) This includes dancing cheek to cheek, rocking a baby to sleep on the shoulder, and sleeping the same bed with someone. 3. Since radioactive iodine is excreted in urine, feces, sweat and saliva; therefore, contact with these substances by other should be avoided. 4. Use separate wash cloths and towels as the rest of the household 5. Flush the toilet at least twice after each use and wipe off the seat if necessary 6. Do not allow anyone to eat or drink from anything that you have eaten from/used 7. Avoid kissing and sexual contact 8. Keep yourself well-hydrated to ensure that the radioactive iodine is removed from the system in a timely manner Response to this treatment depends on the individual patient, yet once the treatment is administered, you should begin to see improvement in about two weeks. Usually, the maximum effect is seen within 3 months of treatment. Some patients may actually become hypothyroid as a result of this therapy and will need lifelong therapy as a result.

This answer was written by Tracy DeJarnette, PharmD candidate

For more information:

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Response by:

Robert James Goetz, PharmD, DABAT
Assistant Professor of Pharmacy Practice
College of Medicine
University of Cincinnati

Jan Scaglione, MT, PharmD, D.ABAT
Assistant Professor of Pharmacy Practice
College of Medicine
University of Cincinnati