Test Overview
A thyroid and parathyroid
ultrasound is a type of imaging test. It checks the
thyroid gland and parathyroid glands. A thyroid ultrasound can help
measure the size and shape of the thyroid gland. But it can't tell how well
the thyroid gland is working. Ultrasound also may be used to check the four
parathyroid glands that lie behind or next to the thyroid.
The thyroid gland makes a
hormone called thyroxine. This hormone controls how fast the body converts food into
energy (metabolism). Parathyroid hormone (PTH) is made by the
parathyroid glands. It controls the amount of calcium and phosphorus in the
blood.
During a thyroid and parathyroid ultrasound, a small
handheld device called a transducer is passed back and forth over the neck. This makes a picture of the thyroid gland and parathyroid glands.
Why It Is Done
A thyroid and parathyroid ultrasound is
done to:
- Check a lump (thyroid nodule) in the
thyroid gland. A thyroid ultrasound can usually show the difference between a
solid thyroid gland nodule and a simple fluid-filled sac (cyst).
- Find out if the thyroid gland is too large. A
thyroid ultrasound may also be used to keep track of the size of the thyroid
gland during treatment for a thyroid problem.
- Guide the placement of the needle during a thyroid
biopsy.
- Look for enlarged
parathyroid glands caused by disease. Normal parathyroid glands are often
hard to see on ultrasound. And they can't be felt during a physical exam.
But abnormal parathyroid glands may be enlarged and easily seen by
ultrasound.
How To Prepare
Talk to your doctor if you have any
concerns about the need for the test, its risks, how it will be
done, or what the results may mean. To help you understand the importance of
this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
This test is
usually done by a
radiologist or by an ultrasound technologist. It is
done in an ultrasound room in a doctor's office or hospital.
You
may be asked to undress above the waist. And you may drape a paper or cloth covering
around your shoulders. Remove all jewelry from your head or around your
neck.
You will lie on your back on a high table with your neck
stretched out. You'll have a pillow under your shoulders. Gel will be spread on your
neck. This helps the sound waves pass through better. (They do not pass easily through
air.) A small water-filled bag or gelatin sponge might be placed over your
throat. This also helps to conduct the sound waves. The transducer will be pressed against
your neck (or against the water-filled bag or gelatin sponge, if used). Then it will be
moved back and forth over your neck. A picture of your thyroid gland and the
tissue around it can be seen on a video screen. You may be asked to turn your
head away from the side being scanned so your jawbone is out of the way.
The test takes about 30 minutes. You may be asked to wait until the
radiologist has reviewed the information. The radiologist may want to do
more ultrasound views of your neck.
How It Feels
The gel may feel cold when it is put on your neck. Keeping your neck extended during the test may cause some discomfort. But you should not feel discomfort from the transducer or sound waves. You will
be able to breathe and swallow normally during the test. You will not hear
the sound waves.
Risks
There is very little chance of a problem from this test.
A thyroid ultrasound
test does not use radiation. It is safe to use during pregnancy and will not
harm your growing baby.
Results
A thyroid and parathyroid
ultrasound is a type of imaging test. It checks the
thyroid gland and parathyroid glands. The results of this test are usually ready in 2 to 3 days.
Thyroid and parathyroid ultrasound| Normal: | The thyroid gland and parathyroid glands are
the right shape and are in the right place. |
|---|
The glands are not too big or too
small. |
No growths or other problems are
seen. |
| Abnormal: | The thyroid gland is too big, or a growth (thyroid nodule) or
cyst is seen in the thyroid gland. A thyroid gland that is too big is called a goiter. |
|---|
The parathyroid glands are too
big. |
What Affects the Test
You may not be able to
have the test, or the results may not be helpful, if:
- You are not able to stay still during the
test. Movement can affect the quality of the ultrasound
picture.
- You have an open wound in the area that needs to be
viewed.
What To Think About
- A radioactive thyroid scan and radioactive
iodine uptake (RAIU) test are nuclear medicine tests. They use a radioactive
substance to see how well the thyroid is working and to find thyroid problems.
To learn more, see the topic
Thyroid Scan.
- A thyroid ultrasound does
not use a radioactive substance. It is easier to do. And it costs less
than a radioactive thyroid scan or RAIU test. But a thyroid ultrasound does not
show how well the thyroid gland is working.
- A thyroid ultrasound may be done at the same time as an RAIU
test. RAIU testing is used more often than a thyroid ultrasound to find
problems such as
hyperthyroidism. A thyroid ultrasound can be used to
find different types of thyroid problems, especially problems such as
thyroid nodules.
- Thyroid nodules are common, especially in women and older
people.
- Thyroid ultrasound can usually show the difference between
a cyst, a solid nodule, or another type of mass that needs more testing. A
fluid-filled sac that is smooth and round and that does not have any particles
floating in it is likely to be a simple cyst. A lump that does not have any
fluid or that has fluid with floating particles needs to be checked more
closely. If a solid nodule is found, a thyroid
biopsy may be needed.
References
Other Works Consulted
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Credits
ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Kathleen Romito, MD - Family Medicine
Specialist Medical ReviewerMatthew I. Kim, MD - Endocrinology