The thyroid gland can be studied a number of ways in the Nuclear Medicine department. Because the thyroid normally needs iodine to make thyroid hormone, a radioactive isotope of iodine is used which allows us to measure how well the thyroid gland is functioning (thyroid iodine uptake). To obtain images of the thyroid gland (thyroid scan), a radioactive tracer will be injected into a vein in your arm.
Test Preparation
- If you are taking thyroid medications, a mineral supplement with iodine, or other medications or preparations that contain iodine, you may be asked to stop them for a time before this test. Check with your physician regarding your medications.
Exam ProcedureThe uptake and scan procedures involve two visits to the Nuclear Medicine Department. On the first day, you will be asked to swallow a small amount of radioactive iodine (in a capsule form). This visit should take about fifteen minutes. The next day, you will return for a measurement of the radioiodine uptake as well as an injection of a radioactive tracer. The tracer allows a picture to be taken of your thyroid gland. This will take one hour or longer. The uptake procedure measures the absorption of the radioactive iodine by your thyroid gland. As you sit comfortably in a chair, a detector will be positioned several inches from your neck, and the amount of the radioiodine in your thyroid gland will be recorded. This will take ten or fifteen minutes. For the scan, you will lie on your back on an imaging table with the camera positioned above you. We will take several images of your thyroid. Each image takes five or ten minutes. Then, a nuclear medicine physician will examine your gland. The imaging procedure will take about 45 minutes. We may then take additional images to look at a certain part of your gland in detail.