A thyroid scan uses a
radioactive tracer and a special camera to measure how much tracer the thyroid gland absorbs
from the blood. The tracer can be swallowed or can be injected into a vein. It travels through your body, giving off radiation signals. The camera "sees" the signals and can measure how much tracer the thyroid absorbs from the blood.
A thyroid scan can show the size, shape, and location of
the thyroid gland . It can also find areas of the thyroid gland that are
overactive or underactive. The camera takes pictures of the thyroid gland from
three different angles. The radioactive tracer used in this test is either
iodine or technetium.
iodine uptake (RAIU) test may also be done to find problems with how the
thyroid gland works, such as
hyperthyroidism. For more information, see the medical
Radioactive Iodine Uptake Test.
Another type of thyroid scan, a whole-body
thyroid scan, may be done for people who have had thyroid cancer that has been
treated. The whole-body scan can check to see if cancer has spread to other
areas of the body.