Thyroid scintigraphy is an exam that serves to assess the functioning of the thyroid. This test is done by taking a medication with radioactive capacities, such as Iodine 131, Iodine 123 or Technetium 99m, and with a device to capture the formed images.
It is indicated to assess the presence of thyroid nodules, cancer, investigate causes of hyperthyroidism or hypothyroidism or inflammation of the thyroid, for example. Check out what are the main diseases that affect the thyroid and what to do.
The thyroid scintigraphy exam is done free of charge by SUS, or in particular, with an average price from 300 reais, which varies a lot according to the place where it is done. After the procedure, the final images of the thyroid can be described as shown in the figure below:
- Result A: the patient has a healthy thyroid, apparently; Result B: may indicate diffuse toxic goiter or severe disease, which is an autoimmune disease that increases thyroid activity causing hyperthyroidism; Result C: may indicate toxic nodular goiter or plummer disease, which is a disease that produces nodules in the thyroid causing hyperthyroidism.
The images formed depend on the uptake of the radioactive substance by the thyroid, and, in general, greater uptake with formation of more vivid images is a sign of greater gland function, as can happen in hyperthyroidism, and a subnormal uptake is a sign of hypothyroidism.
What is it for
Thyroid scintigraphy can be used to identify diseases such as:
- Ectopic thyroid, which is when the gland is located outside its normal location; Dipping thyroid, which is when the gland is enlarged and can invade the chest; Thyroid nodules; Hyperthyroidism, which is when the gland produces excess hormones. Know what are the symptoms and ways of treating hyperthyroidism; Hypothyroidism, when the gland produces less hormones than normal. Understand how to identify and treat hypothyroidism; Thyroiditis, which is inflammation of the thyroid; Thyroid cancer and to check for tumor cells after thyroid removal during treatment.
Scintigraphy is one of the tests that evaluate the thyroid, and the doctor may also request others to help with the diagnosis, such as blood tests that evaluate the amount of thyroid hormones, ultrasound, puncture or biopsy of the thyroid, for example. Find out which tests are used for thyroid assessment.
How the exam is done
Thyroid scintigraphy can be done in just 1 day or in stages divided into 2 days and requires a fast of at least 2 hours. When done in just 1 day, the radioactive technetium substance, which can be injected through the vein, is used to form images of the thyroid.
When the test is done in 2 days, on the first day the patient takes iodine 123 or 131, in capsules or with a straw. Then, images of the thyroid are obtained after 2 hours and 24 hours after the beginning of the procedure. During the intervals, the patient can go out and do his normal daily activities, and in general the test results are ready after about 3 to 5 days.
Both iodine and technetium are used because they are substances that have affinity for the thyroid, and can be concentrated in this gland more easily. In addition to the form of use, the difference between the use of iodine or technetium is that iodine is more suitable for assessing changes in thyroid function, such as hyperthyroidism or hypothyroidism. Technetium is very useful to identify the presence of nodules.
How to prepare for the exam
Preparing for thyroid scintigraphy consists of avoiding foods, medications and medical tests that contain or use iodine or that alter thyroid function, such as:
- Food: do not eat foods with iodine for 2 weeks, being prohibited the consumption of saltwater fish, seafood, shrimp, seaweed, whiskey, canned products, seasoned or containing sardines, tuna, egg or soy and derivatives, such as shoyo, tofu and soy milk;
Watch the following video and see which diet is best for iodine therapy:
- Examinations: in the last 3 months, no exams such as contrast computed tomography, excretory urography, cholecystography, bronchography, colposcopy and hysterosalpingography were performed; Medications: some medications can interfere with the exam, such as vitamin supplements, thyroid hormones, medications containing iodine, heart medications with the substance Amiodarone, such as Ancoron or Atlansil, or cough syrups, so it is important to talk to the doctor to assess their suspension; Chemical products: in the month prior to the exam, you cannot dye your hair, use dark lipstick or nail polish, tanning oil, iodine or iodized alcohol on your skin.
It is important to remember that pregnant or breastfeeding women should not have a thyroid scan. In the case of technetium scintigraphy, breastfeeding should be suspended for 2 days after the examination.
The PCI exam - full body search consists of a very similar exam, however, it is a used device that generates images of the whole body, being especially indicated in case of metastasis investigation of tumors or thyroid cells in other parts of the body. Learn more about full body scintigraphy here.
