A thyroid scan uses a radioactive tracer (iodine or technetium) and a special camera to measure how much tracer the thyroid gland absorbs from the blood. It can show the size, shape, and location of the thyroid gland.
The thyroid gland is located in the lower part of the neck, below Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus).
It is responsible for producing and storing essential hormones that help regulate the heart rate, blood pressure, body temperature, and the rate of chemical reactions (metabolism) in the body, but also is the main part of the body that takes up iodine.
A thyroid scan is performed as an outpatient procedure, usually in the nuclear medicine section of a hospital which is usually part of the radiology department.
During the procedure, first, the patient will be asked to take a drink, or swallow a pill containing the iodine and about 4 hours for the iodine to be taken up by the thyroid.
Then the patient will lie under a scintigraphy camera and the pictures, which correlate directly to the amount of iodine taken up by the thyroid, will be taken. The patient will then leave the hospital, and return in 24 hours to have a second scan performed in the same way.
During this 24 hour period, the patient is asked to take precautions when urinating because the radioactive iodine is removed from the body by the urine, and it is safer to have others avoid contact with patient’s urine during this time.