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

In general, there's nothing you have to do before this test, unless your doctor tells you to.

How It Is Done

This test 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 and 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.

You may be asked to wait until the radiologist has reviewed the information. He or she may want to do more ultrasound views of your neck.

How long the test takes

The test takes about 30 minutes.

How It Feels

Most people don't feel pain during the test. But keeping your neck extended during the test may cause some discomfort. You will be able to breathe and swallow normally during the test. You will not hear the sound waves.

Risks

There are no known risks from having this test.

Results

The results of this test are usually ready in 2 to 3 days.