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Preparation Guidelines

Thyroid Supression Test

Patient Guidelines

PREPARATION:

Absolute fasting of 6 hours, for iodine-based exams.
The patient must use a high dose of T4 (Puran, Euthyrox, Levoid, Synthroid). Check if the referring physician has already prescribed the hormone to perform the test.
Medications to be suspended:
- For at least 90 days or at medical discretion, medicines that contain amiodarone as an active ingredient. In cases of prolonged use of this medication, the suspension time may be longer than this period;
- Medications containing iodine, such as cough syrup, vitamins and vitamin supplements enriched with iodine or containing red dye (erythrosine) must be suspended for at least 30 days. Check the package insert or label of the medicine;
There are no limitations on the use of analgesics, antibiotics and anti-inflammatories, as long as they do not contain red dye (erythrosine);
Topical solutions and use of cosmetics: topical solutions containing iodine, such as Povidine, iodized alcohol, Schiller’s test (gynecological exam), as well as the use of red/pink lipstick (containing edible red dye – erythrosine) should not be used for at least 15 days;
MEDICATIONS SHOULD ONLY BE WITHHELD UNDER SUPERVISION FROM THE ATTENDING PHYSICIAN;
Iodinated radiological contrasts should not be used for at least 30 days before the exam;
Avoid walks on the beach and bathing in the sea, in addition to using suntan lotions for 15 days before the exam. (sunscreens are allowed);
This test is not recommended for pregnant or breastfeeding women;
Do not forget to bring any imaging exams (such as thyroid ultrasound).
If you have any questions about medications, please contact our call center.

DIET:

1) The goal of the diet is to reduce as much as possible the amount of iodine that comes from food and drinks. This is necessary to increase therapeutic efficacy/exam accuracy.

2) Check the product label if there is a reference to iodine or erythrosine dye in its composition or if there are any of the ingredients listed below.

3) Do not confuse sodium with iodine, for food or medicines that contain only sodium are allowed.

Foodstuffs that should not be consumed for 15 days prior to therapy.
Salt	All foods containing iodized salt (snacks, fried potatoes, cookies, etc.). Custom-ordered Non-iodized salt is allowed.
Fish and food from the sea	All seafood (oysters, fish, seaweed, shrimp, etc.). Freshwater fish is allowed.
Meat and derivatives	Smoked meat, sun-dried meat, meat broth, sausages (salami, bologna, mortadella, ham, bacon, sausage). All fresh meats are allowed.
Eggs, sauces, oils and seasonings	Egg yolk (egg whites are allowed), mayonnaise, soy oil and sauce, industrialized tomato sauce, ketchup, industrialized seasonings and broths (Sazon, Knorr, etc). Other seasonings, such as vinegar, olive oil, parsley, oregano, homemade tomato sauce, rosemary, thyme, corn/sunflower oil are allowed.
Fresh fruit	Strawberry, cranberry, blueberries.

Leaves and vegetables	Watercress, celery, Brussels sprouts, cabbage, artichokes, unpeeled potatoes and spinach.
Grains and flours	Soybeans and derivatives. Chestnuts, peanuts and salted nuts. Other grains (e.g., rice, beans, corn, wheat) and flour are allowed.
Canned goods and preserves	All canned vegetables (such as olives, pickles, sauerkraut, etc.), canned or syrupy candies and prunes.
Sweets and drinks	All chocolates, candies made with eggs and/or milk, candies and drinks containing red/pink dye. Instant or instant coffee, industrialized teas, coconut water and dark soft drinks. Natural juices and teas, clear soft drinks, light beer, and white wine are allowed. Vegan sweets, honey and molasses are also allowed.
Dairy	All milk of animal origin and its derivatives (butter, cheese, cottage cheese, yogurt, ice cream), soy milk and tofu (soy cheese). Other milks, such as oats, almonds, rice and unsalted margarine, are allowed.
Breads and pastas	Industrialized breads, pizza and all pasta made with eggs/milk.
Food Supplements	All food supplements (e.g. Whey protein, casein, creatine, etc.) should be suspended.

HOW IS THE EXAM PERFORMED?

After filling out the registration form at the reception desk, the patient will undergo a brief clinical interview to check their data and exam preparations (it is important for this exam that the patient uses a high dose of levothyroxine). Then, the patient will be sent to the drug preparation room, where the radioactive material will be administered (intravenously, if Technetium is used or orally, if Iodine is used).

The patient will either be instructed to wait 20 minutes and will then be sent to the examination room for image acquisition (if the examination is performed with 99mTc).

Or the patient will be discharged and instructed to return to the clinic after 4 to 6 hours (optional) and 24 hours after oral iodine administration (if the test is performed with Iodine).

In the examination room, the patient will be positioned on the device’s gurney and must remain lying motionless for approximately 20 to 30 minutes to acquire the images.

The acquisition time varies, depending on the amount of the drug retained in the thyroid.

At the end of the exam, the patient will be discharged and should resume their routine medications.

Note: Nuclear medicine exams are not recommended for pregnant and breastfeeding women.

OE 063 – Version: 06/2024

Made by: DIMEN Technical Team