Thyroid Scan

The thyroid gland, which is found in the neck, controls how quickly the body uses energy and makes proteins. It also controls how sensitive the body is to other hormones. In these processes the thyroid produces hormones, which regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. The most common problems of the thyroid gland consist of an overactive thyroid gland, referred to as hyperthyroidism, and an underactive thyroid gland, referred to as hypothyroidism.

A thyroid scan is used to study the structure and function of the thyroid gland, including size, shape and location. A radioactive tracer material allows the nuclear medicine physician to examine the thyroid function.

Procedure

A thyroid scan is a two-day procedure. On the first day, you will be asked questions regarding any prior tests, medication, symptoms or family history of thyroid problems. You will then be given one to three capsules containing radioactive iodine that will accumulate in your thyroid. The process takes 30 minutes. After consuming the pills, you may continue to eat and drink anything you please. Patients sometimes are asked to return in four to six hours and at 24 hours for thyroid assessment.  This part of the examination is referred to as the Thyroid Uptake.

The actual scanning procedure will be performed on the second day, for which no special preparation is required. You will lie comfortably on a scanning table while images of your thyroid are produced during a 30-minutes session. After the exam, the technologist will process your images using a computer. A nuclear medicine physician will evaluate the images and dictate a report, which will be sent to your physician.

Preparation

Do not consume any oral iodides (such as Lugols solution or vitamins containing iodine) for two weeks preceding the exam and refrain from eating fish, kelp or other iodine-rich foods for at least five days prior. Occassionally, you may need to discontinue certain types of medication up to a week before the appointment. For example, you should not take any thyroid hormones or any thyro-suppressive drugs such as PTU. You must not have undergone X-ray exams involving iodine contrast, such as an IVP or CT, during the past two to three months because contrast media can interfere with the thyroid examination.

Side Effects and Possible Complications

The iodine used for this exam is inorganic and will not cause reactions like those sometimes experienced with the contrast used in X-ray procedures. If you are nursing an infant or may possibility be pregnant, please speak with your referring physician before your scheduled appointment.

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