Iodine-131 therapy is given to patients with thyroid cancer
who have had a total thyroidectomy (surgery) and have stopped
all thyroid medications for several weeks, but a iodine body
scan shows that they still have activity in the residual
thyroid tissue and/or in metastatic lesions.
The purpose of Iodine-131 for thyroid ablation is to destroy
all functioning thyroid tissue.
It has been shown that the use of thyroid hormones after
surgery decreases the recurrence rate of cancer — a
rate that is further decreased when radioiodine is used postsurgically.
Given in capsule form, Iodine-131 will dissolve in the stomach
and travel systemically throughout the body, being absorbed
by whatever thyroid tissue is remaining. The Iodine-131 that
is not absorbed will be excreted from the body by either
or all of the following three routes:
• Saliva • Urine • Sweat
The radioiodine from your treatment will remain in your
body only temporarily. Most of the radioiodine not collected
by your thyroid gland will be eliminated during the first
two days after your treatment. It leaves the body primarily
through your urine, but very small amounts may leave in your
saliva, sweat and during a bowel movement. 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. At the end
of treatment, no radioiodine remains in your body.
The amount of radioiodine in your body during treatment
is small. Although there is no evidence that the radiation
from this amount will cause any problems, it makes senseto
take steps to minimize exposure, no matter how small. If
you take these simple precautions during the first few days
after your treatment, you can reduce or eliminate the possibility
of radiation exposure to others.
There are three basic principles to remember:
• Distance. The greater the distance
you are from others, the less radiation they will receive.
Even an increase in distance of a few feet will greatly reduce
the exposure. So try not to remain in close contact with
others for longer than necessary.
• Time. Radiation exposure to others
depends on how long you remain close to them. You should
try to minimize the time spent in close contact with others.
• Hygiene. Good hygiene minimizes
the possibility that other people will be contaminated with
the radioiodine that leaves your body. Since most of it leaves
your body in the urine, good toilet hygiene and careful and
thorough washing of your hands will reduce the possibility
Below are guidelines, recommended by the Society of Nuclear
Medicine, that will help you reduce exposure to others.
Your physician can best recommend which guidelines are important
for you and how long they should be followed. Ask your doctor
for more information.
• Sleep alone for the first few days after your treatment.
During this period, avoid kissing or sexual intercourse.
Also avoid prolonged physical contact, particularly with
children and pregnant women; the thyroid glands of children
and fetuses are more sensitive to the effects of radioiodine
than those of adults.
• If you have a baby or are taking care of one, your
doctor can best instruct you on the following guidelines.
You probably can do what is necessary to care for your baby,
but it is preferable not to have the baby too close, such
as sitting in your lap, for more than a short time during
the first two days after treatment.
• If you have been breastfeeding your baby, you must
stop because radioiodine is secreted in breast milk. Discuss
with your doctor when you will be able to resume breastfeeding.
• If you are pregnant or think you may be, tell your
doctor because radioiodine treatment should not be given
during pregnancy. Also, if you are planning to become pregnant,
ask your doctor how long you should wait after treatment.
• Wash your hands with soap and plenty of water each
time after you go to the toilet.
• Keep the toilet especially clean. Flush it two or
three times after each use.
• Rinse the bathroom sink and tub thoroughly after
you use them. Clean bathroom practices will reduce the chances
of others becoming contaminated from the radioiodine in your
salvia and sweat.
• Drink plenty of liquids such as water and juices.
This will make you urinate more frequently and help the radioiodine
to leave your body more rapidly, thus lowering the amount
in your body.
• Use separate (or disposable) eating utensils for
the first few days and wash them separately. This will reduce
the chance of contaminating other family members with the
radioiodine in your saliva.
• In most cases, normal activities may be resume 72
Based on Nuclear Regulatory Commission requirements, your
release from the hospital will be based on the amount of
exposure you are likely to give to any individual with whom
you may come in contact. This will be calculated by the our
medical physicist. In most cases, patients receiving this
treatment return home on the same day of administration of
, please contact our medical
physicist at 732-923-6811, or your nuclear medicine physician
here for the informational brochure (pdf),
available as a PDF (portable document format) file.
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