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Thyroid Cancer: Finding It and Treating It Using Radioiodine (large print version of #4908) (6273)

Thyroid Cancer: Finding It and Treating It Using Radioiodine (large print version of #4908) (6273) - Clinical Hub, Patient Education, Health and Nutrition Facts For You, Cancer, BMT, Hematology


Thyroid Cancer
Finding It and Treating It Using Radioiodine

Your doctor has referred you to
Nuclear Medicine to learn more
about the extent of your thyroid
cancer, and perhaps even for
treatment of the cancer. Please
feel free to direct any questions
or concerns you might have
either to your doctor or to one of
our Nuclear Medicine doctors.

What Does the Thyroid Do?

The thyroid is a small, butterfly-
shaped gland that sits below the
Adam’s apple. It helps to control
your body’s metabolism. It
works to produce thyroid
hormones, which travel
throughout the body. When the
thyroid is working as it should, it
also takes up iodine. Thyroid
cancer cells which take up iodine
are “well differentiated.” This
means that these cancer cells
have not changed much. If they
are well differentiated, they are
still working in many ways as
you might expect normal thyroid
gland cells to work.

What Kinds of Thyroid Cancer
Are There?

The two most common forms of
thyroid cancer which can be
treated are papillary and
follicular. These are the types
that often take up radioiodine just
like normal thyroid tissue.

What Is the Treatment for
Thyroid Cancer?

Thyroid cancer treatment can be
thought of as a process. The
process includes:

ξ Surgery to remove the
thyroid gland.
ξ Thyroid ablation to rid the
body of “left over” thyroid
cells with use of a
radioiodine capsule.
ξ Blood tests to check TSH
and thyroglobulin levels.
ξ Total body radioiodine
metastatic survey scans to
check for remnants of the
thyroid as well as for any
spread of cancer cells.
There are special
instructions listed below.
The scans may be done
more than one time in order
to follow progress of
ξ Hormone replacement to
replace the hormone once
made by the thyroid gland.

The first line of treatment for
most thyroid cancer is surgery.
About 4 weeks later, a dose of
radioactive iodine is used to
destroy any thyroid tissue that
may have been left after the
surgery. After the thyroid gland
is destroyed, patients need pills
to replace the thyroid hormone
that would have been made by
the thyroid gland.

What Is Thyroid Ablation?

This is done in the Nuclear
Medicine. It is often used to
remove (ablate) any thyroid
tissue that may remain behind in
your neck after surgery. This is
done by giving you some
radioactive iodine that will
destroy the small amount of
thyroid tissue left in your neck
after surgery. You do not need to
remain in the hospital after this
treatment. Most of the time this
is done a month after surgery and
a capsule of radioactive iodine is
given when the TSH test is high
(greater than 40 units).
Sometimes your endocrine
physician uses Thyrogen ®, a
synthetic thyroid stimulating

How Does Radioactive Iodine

Iodine is taken up by the normal
thyroid gland and most (~ 70%)
thyroid cancers. When the cells
take up iodine, they also take up
radioiodine or iodine-131, which
is a radioactive form of iodine.
Iodine that is radioactive can be
used to find and treat thyroid
cancer. It is one of the oldest and
best forms of cancer treatment
for any thyroid cancer that will
take up radioiodine. It destroys
cancer cells.

What Is a Metastatic Survey?

This survey scan is also done in
Nuclear Medicine for patients
with thyroid cancer. Most often
it is done after thyroid surgery
and ablation, and again at other
future times as needed. It is used
to find out if there is any spread
of cancer (metastases) to other
parts of your body.

For the survey, you will be given
a capsule of radioactive iodine to
swallow. It will travel to any
thyroid tissue and to most thyroid
metastases. You will return to
Nuclear Medicine 2-7 days later,
and images of your body will be
made. These will show how
much thyroid tissue is left in your
neck and whether or not there is
any spread of the cancer.

How do I Prepare for a
Metastatic Survey?

If you have been taking any
thyroid hormone pills, you might
be asked to stop them about a
month before the survey, since
they will impact the test. If you
stopped your thyroid replacement
pills, you will be told when you
should start taking these pills
again after taking the radioiodine
and scan. Sometimes another
method is used where we inject
synthetic human thyroid
stimulating hormone
(Thyrogen®) so you would not
need to stop thyroid hormone
therapy. Thyrogen® has also
been approved for thyroid
remnant ablation, and may be
used in treatment of thyroid
metastases. There is a special
schedule of injections, dosing
with radioiodine, blood tests, and
thyroid scanning.

When the survey is scheduled,
you will also be scheduled to
have a TSH blood test done
about two days before the survey.
A sample may also be taken to
measure serum thyroglobulin.

You may be asked to maintain a
low iodine diet for about ten days
in order to allow the test to work
better. To do this, you should
avoid milk & dairy products,
seafood, kelp, bread cereal and
many seasonings (above all salt
which has had iodine added).
Most fruits, vegetables and meats
that have not been processed are

Please tell us if you have had an
x-ray using contrast in the last
few weeks. You must not be
pregnant or breast feeding when
you receive radioiodine. You
should not plan to become
pregnant in the next 6 months.
You should not father a child for
6 months.

How Is Metastatic Thyroid
Cancer Treated?

If your survey shows spread of
thyroid cancer to other parts of
your body, your doctor may
discuss treatment with a larger
amount of radioactive iodine than
that used for simple thyroid

How Should I Take Care of
Myself after I Receive

Most of the radioiodine that is
not taken up by thyroid tissue
will leave your body within
about two days. Most is lost
through your urine, but some is
also released in saliva, sweat, and
stool. In order to help remove
the extra radioactivity, you
should drink extra fluids and
empty your bladder often (about
every 1-2 hours or so) for the
first 2 days. During the first two
days after the dose, drink plenty
of juices and water. You should
try to have at least one bowel
movement each day. Add fiber
and prune juice to your diet if
needed. You may need a laxative
if you are having trouble with
bowel movements. You might be
advised to take lemon candies to
increase saliva secretion after
you take the radioiodine capsule.


Radiation Safety Measures for

The dose of radioiodine used to
perform a metastatic survey is
most often small. Doses used in
thyroid ablations are greater, with
the largest doses used for
treatment of thyroid cancer
metastases. People around you
are at very low risk from the
radiation. There are things that
you can do in the first two to
three days to lessen the risk for

 Do not return to work
until the next day.
 Limit your time in public
 Do not travel by airplane
or prolonged car trips for
two days.
 Maintain an arm's length
distance from other people
if you will be with them
for long stretches of time,
and double this distance
from pregnant women and
children (2 arms lengths).
The amount of radiation
exposure will decrease
quickly as the distance is
increased. Maintain this
for 4 days.
 Flush the toilet twice after
using it. Brush once
under the rim of the toilet
with the toilet brush and
reflush. If you can, use a
toilet that others won’t
 Avoid sharing of eating
utensils. After use, you
can wash your utensils as
 Use fluids and lemon
candies, as described
 Sleep alone in bed for 4
 Avoid close contact with
children and pregnant
 If you think you are
pregnant, inform your
doctor because
radioiodine should not be
given to pregnant women.
After you receive
radioiodine, you should
avoid getting pregnant for
about six months.
 Radioiodine will show up
in breast milk. Inform
your doctor if you are
breast feeding.
 You should not try to get
pregnant or father a child
for at least six months
after treatment with

Frequently Asked Radiation

Can I continue breast feeding?

Absolutely not! The radioiodine
absorbed by a breast feeding
infant can lead to permanent
thyroid gland problems. External
radiation exposure to the baby
will result from being close to the
mother’s breast (radioiodine will
accumulate in the breast of a
breast-feeding mother) and being
close to the mother’s radioactive
thyroid. Therefore, breast
feeding must be stopped well
before the mother’s radioiodine
treatment. Nursing may resume
after the birth of your next child.

I am still lactating. Is that a

Yes, a big one! The radiation
dose to the lactating breast can be
large. Lactation must be fully
ended well before treatment. If
you abstain from nursing for 2-3
months before treatment, we can
be sure that lactation (and the
ability of the breast to
concentrate large amounts of
iodine) doesn’t increase your
radiation exposure.

I have children at home? What
should I do?

Plan to limit contact with them
for at least 4 days. Always keep
in mind the “arm’s length rule.”
To resist the temptation of
children coming close to you
during this time, it is best to
make plans for the children to
spend most of this time with
other family members.

I am planning on staying at a
hotel for a few days just to play
it safe. What do you think?

We strongly advise you not to do
this. Although reassuring to your
loved ones, this will expose the
public (housekeeping staff and
other patrons) to radiation. We
know that the toilet you use will
be a source of radiation exposure
since most of the radioiodine is
passed through the urine. This is
why we advise you to use your
own bathroom for a few days and
avoid using public bathrooms.

How long should I wait to get
pregnant after having
radioiodine treatment?

We advise you to wait at least 6
months even though it cannot be
proven whether 6 months is
better than 4 months or 8 months.
It is just a good, conservative
amount of time.

Do I need any tests prior to

Hospital policy mandates a
pregnancy test on the day before
or the day of treatment for all
women of childbearing age.

I don’t need a pregnancy test
because my husband had a
vasectomy, right?

Wrong! Please refer to the
answer above.
How do all these radiation
safety measures apply to pets?

Treat them as people or, better
yet, children. Their thyroid
glands are much more sensitive
than adult human thyroid glands,
so besides the “double arm’s
length rule,” we also advise you
to limit holding your pets for 4

Any Further Questions?

If you are a UW Health patient
and have any other questions or
concerns, we will gladly help you
with them. You can reach us at
(608) 263-1462. If you are a UW
Health patient and live out of the
area, call 1-800-323-8942 and
ask for the Nuclear Medicine

Your health care team may have given you this information as part of your care. If so, please use it and
call if you have any questions. If this information was not given to you as part of your care, please check
with your doctor. This is not medical advice. This is not to be used for diagnosis or treatment of any
medical condition. Because each person’s health needs are different, you should talk with your doctor or
others on your health care team when using this information. If you have an emergency, please call 911.
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by the Department of Nursing. HF#6273