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This information is specifically for patients who will be treated with radioiodine, a radioactive form of iodine. It includes some special instructions to follow during and after your treatment.


Why will I receive radioiodine treatment?
Your doctor has advised you to receive radioactive Iodine I-131 (radioiodine) because it is the most appropriate treatment for your thyroid condition. The radiation given off by this form of iodine decreases the function of thyroid cells and inhibits their ability to grow, which is the desired and beneficial medical effect of the treatment.

Who is the best source of information concerning my
condition and treatment?
Your doctor is the best source of information concerning your condition and treatment. This pamphlet is designed to help answer some of the most frequently asked questions regarding radioiodine treatment. It lists some guidelines for you to follow for a short time immediately after your treatment (usually no more than 2 to 5 days, depending on your treatment and your doctor’s instructions). You can download this brochure to use as a guideline in discussing your particular situation with your doctor to help you make more informed decisions.

How does radioiodine work?
The thyroid gland accumulates iodine from the food you eat and uses this iodine to perform its normal function, which is to make thyroid hormone. Radioiodine is used to treat overactive thyroid glands and certain kinds of thyroid cancer. It is taken up mainly by the thyroid gland. In the treatment of hyperactive thyroid glands, radiation from the radioactive iodine damages a portion of the thyroid gland to reduce its activity. Larger doses of radioiodine may be used after thyroid cancer surgery to destroy any remaining diseased thyroid tissue.

How safe is radioiodine?
The practice of treating one’s thyroid with radioiodine is a common, well-accepted form of treatment that has been used medically all over the world for more than 50 years. Most of the radiation from the radioiodine will be received by your thyroid gland. However, the other tissues in your body will receive some incidental radiation. This small amount of radiation typically does not produce any adverse effect.

How long does the radioiodine stay in my body?
The radioiodine from your treatment will temporarily remain in your body. Most of the radioiodine not collected by your thyroid gland will be eliminated within the first 2 days after your treatment. Radioiodine leaves your body primarily in your urine, but very small amounts may leave in your saliva, sweat, and feces.

The amount of radioiodine remaining in your thyroid tissue is responsible for the desired medical effect. However, this amount also decreases rapidly. This means that the possibility of radiation exposure to you and others is reduced with time. Over time, no radioiodine remains in your body.

Can others be exposed to radiation from the radioiodine given to me?
Exposure to radiation from the radioiodine in your body may occur if other people remain very close to you for extended periods of time. Try to keep the time you spend in close contact with others to a minimum. Contamination with radioiodine can occur if it is deposited in any place where other people may have contact with it. For instance, if some of the radioiodine in your saliva gets on the bathroom counter as you brush your teeth and then on to someone’s hands, contamination has occurred. If this radioiodine is then taken into someone’s body from the hands or from food that has been touched, it will cause a small amount of radiation exposure to that person.

However, radioiodine decays and disappears by itself as part of the physical processes that make it radioactive. For example, it will not remain on the counter indefinitely because its quantity is reduced by one-half every 8 days. This is what is meant when it is said that the "half-life" of radioiodine is 8 days.

How can I reduce radiation exposure to others?
The amount of radioiodine in your body during the treatment is small. Although there is no evidence that the radiation from this amount of radioiodine will cause any problem, it makes sense to take steps to minimize exposure, no matter how small. If you follow simple precautions during the first few days after your treatment, you can eliminate or reduce the possibility of radiation exposure to others.
 

	Radiation Exposure
	Three basic principles to keep in mind:
	1 – Time
	The amount of radiation exposure that another person may receive depends on how long you remain close to them. You should try to minimize the time spent in close contact with others.
	2 – Distance
	The greater the distance you are from others, the less radiation they will receive. Even an increase in distance of just a foot or two will greatly reduce the exposure they receive. Try not to remain in close contact with others for longer than is needed.
	3 – Hygiene
	Good hygiene will minimize the possibility that other people will be contaminated with the radioiodine that leaves your body. Most of the radioiodine leaves your body in your urine, so good toilet hygiene and careful and thorough washing of your hands will reduce the possibility of contamination. Since radioiodine may also leave your body in your sweat, consider skipping your workout in the gym for a day or two.
	Important guidelines to help you apply these basic principles:
	Your doctor can best recommend which guidelines are important for you and how long you should follow them. Do not hesitate to ask your doctor for more information.
	Sleep alone for the first few days after your treatment. During this period, avoid kissing or sexual intercourse. You should also avoid prolonged physical contact. It is particularly important in regards to contact with children and pregnant women because the thyroid glands of children and the unborn are more sensitive to the effects of radiation than those of adults.
	If you are pregnant, or think you could be, tell your doctor because radioiodine treatment should not be given during pregnancy. Also, if you are planning to become pregnant, consult with your doctor who can advise you on how long you should wait after treatment.
	If you have a baby, or you are taking care of one, be sure to get specific instructions from your doctor. You can probably do all the things necessary to care for your baby, except breastfeeding. It is preferable not to keep the baby too close to your body, such as sitting in your lap, for more than a short time during the first two days after your treatment.
	If you have been breastfeeding your baby, you must stop. Radioiodine passes into the breast milk and may cause unwanted effects in the nursing baby, such as an underactive thyroid. Discuss with your doctor when you can resume breastfeeding.
	Wash your hands thoroughly with soap and plenty of water each time you go to the toilet.
	Keep the toilet especially clean. Be sure to flush it 2 or 3 times after each use.
	Rinse the bathroom sink and tub thoroughly after you use them. Clean bathroom habits will reduce the chances of others becoming contaminated by the radioiodine in your saliva and sweat.
	Drink plenty of liquids such as water or juices. This will make you urinate more frequently and help the radioiodine to leave your body more rapidly, thus lowering the amount of radioiodine remaining in your body.
	Use disposable eating utensils for the first few days after treatment, or wash your utensils separately. This will reduce the chance of contaminating other family members with the radioiodine in your saliva.
	Use separate towels and washcloths. Launder your bath towels, bed linens, and underclothing separately.
	IMPORTANT – Please note that you will only need to carry out these guidelines for the first few days following your treatment. Your doctor will give you specific details as to how long you should follow these precautions.