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Thyroid cancer patients with papillary or follicular thyroid cancer often receive a dose of radioactive iodine (RAI) about two months after their surgery in an attempt to destroy (ablate) any remaining thyroid cells in their bodies.
Most of these thyroid cancer patients also undergo whole-body radioiodine scans at periodic intervals, using a “tracer” dose of RAI. If their scan is not “clean,” they may then receive treatment with a larger dose of RAI in an attempt to eliminate remaining thyroid cells.
In preparation for an RAI scan or RAI treatment, patients are usually asked to go on a low-iodine diet (LID). The diet is to prepare for the RAI. The patient follows the diet when preparing for RAI either by temporarily stopping levothyroxine (withdrawal) or by receiving injections of Thyrogen (recombinant TSH) while continuing on levothyroxine.
The purpose of a low-iodine diet is to deplete the body of its stores of iodine, to help increase the effectiveness of the radioactive iodine scan or treatment. The premise is that when the radioactive iodine is administered, the thyroid cells will “suck” up the iodine, because the body has been so depleted.
This diet is for a short time period. The usual time period is around two weeks (14 days) or slightly more. The diet usually begins around two weeks before testing and continues through the testing and treatment period. However, recommendations for the time period can vary, depending partly on the individual patient’s circumstances.
The following is a combination of diet guidelines from several ThyCa medical advisors (who use urine iodine testing to check patients' iodine levels), from researchers' findings presented in medical journals and at ThyCa events, and from input from our 22-member Medical Advisory Council. Your physician may have different guidelines. Please check with your doctor before you start the diet.
Avoid These Foods and Additives
Avoid the following foods, starting when instructed by your physician before your radioactive iodine test or treatment. Continue as instructed until after your radioactive iodine treatment (often for about 24 hours after). These foods and ingredients are high in iodine (over 20 mcg per serving, according to researchers' presentations at our conferences).
Limit the Amounts of these Foods
Some diets from thyroid cancer specialists and researchers recommend limiting the daily intake of foods that are moderate in iodine: 5 to 20 mcg per serving.
What About Restaurant Foods and Fast Food?
Although restaurants generally use non-iodized salt, it is not possible to know whether a particular restaurant is using iodized salt or sea salt. The manager or serving staff may not know what product is being used, or whether butter or other dairy products are present in foods. The ingredients that chain and fast-food restaurants use may change.
Therefore, we suggest that you avoid restaurant foods other than plain juices or soft drinks, or the inside of a plain baked potato. For most restaurant foods, there is no reasonable way to determine which restaurants use iodized salt. Avoid if in doubt.
What About Manufactured and Processed Foods?
Some published low-iodine diets and researchers' presentations allow salty processed foods and other processed foods. Some of these foods include potato chips and cured and corned foods such as hot dogs, ham, corned beef, sauerkraut, bacon, sausage, and salami.
Currently, manufacturers of processed foods in the USA generally use non-iodized salt. However, food processing techniques can change and labels are not always accurate or up to date.
For that reason, if fresh foods are available, many patients prefer to eat fresh foods during the short period of being on the low- iodine diet. They avoid processed food, because it is not known for sure whether or not iodized salt has been used. For any processed food, it is also important read the label to be sure there is no Red Dye #3.
In the past some patients have contacted manufacturers asking whether or not they used iodized salt in their products or iodine-containing cleansers or sanitizers for their equipment and surfaces involved in food processing. Doing this is NOT recommended for the following reasons:
Read the ingredient labels on all packaged foods and spices. Some support group participants have compiled lists of brands of processed and packaged foods low in iodine. A list is being reviewed for addition to ThyCa's web site and as an appendix to this cookbook.
Foods That Are Fine to Eat on the Low-Iodine Diet
The low-iodine diet consists mostly of fresh, low-fat, low-calorie foods. Because of this, following this diet greatly reduces the tendency to gain weight while hypothyroid.
The following foods and ingredients are fine to eat. You do not need to limit the quantity, except as noted.
Food prepared from fresh meats, fresh poultry, fresh or frozen vegetables, and fresh fruits should be fine for this diet, provided that you do not add any of the iodine-containing ingredients listed above. The cookbook also has a handy snack list.
What if it's not on the "okay" list here?
A Final Note
The key to coping well with this diet is being prepared ahead of time, especially if you are preparing for RAI by stopping your levothyroxine pills and becoming hypothyroid. Before you start becoming hypothyroid, prepare the basics and freeze. You do not want to be making chicken stock while you are hypothyroid.
Remember also the handy snack list. We suggest that you stock up on snack items from the list for times when you do not feel like cooking.
We encourage you to use our Low-Iodine Cookbook for variety and enjoyment of low-iodine meals and snacks. Thousands of other thyroid cancer survivors have used and enjoyed our recipe collections.
Download the Free ThyCa Low Iodine Cookbook for more information and for recipes.
Download the One-Page Summary in
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Your Home Stay or Hospital/Home Stay
After receiving RAI for a scan, you will go home immediately. After your RAI treatment dose, you may be sent home immediately, or you may stay in the hospital for one or more days. The size of the treatment dose that involves a hospital stay varies from one jurisdiction to another, and sometimes from one hospital to another in the same jurisdiction. Currently, patients go home immediately after larger doses of RAI than in the past. Your home circumstances, such as whether there is an infant at home, may affect the decision about going home or staying in the hospital for a day or more after your treatment dose.
Below are samples of guidelines from informational materials. Please note that your physician and hospital may have different procedures and guidelines. Discuss your questions and concerns with your doctor.
Information If You Go Home Immediately After Receiving RAI
As your doctor will have explained to you, you will be receiving radioactive iodine as your treatment. Radioactive iodine decreases the function of thyroid cells and inhibits their ability to grow. It is given to you in liquid or pill form and goes directly to the thyroid gland where it is absorbed by the thyroid tissue. Most of the radioactive iodine will be received by your thyroid gland. Any radioactive iodine not collected by the thyroid gland will be eliminated during the first few days through urine, feces, saliva and sweat. The following steps listed below will help assure that the excreted radiation from your body does not contaminate the environment or cause harm to other people.
For information about possible side effects of radioactive iodine, see the information below in the section about the hospital stay.
What do I do at home?
Information During Your Hospital Stay
As your doctor will have explained to you, you will be receiving radioactive iodine as your treatment. Radioactive iodine decreases the function of thyroid cells and inhibits their ability to grow. It is given to you in liquid or pill form and goes directly to the thyroid gland where it is absorbed by the thyroid tissue. Most of the radioactive iodine will be received by your thyroid gland. Any radioactive iodine not collected by the thyroid gland will be eliminated during the first two days through urine, feces, saliva and sweat. The following steps listed below will help assure that the excreted radiation from your body does not contaminate the environment or cause harm to other people.
How Long Will I Be in Isolation in the Hospital?
After the doctor has given you your treatment you are requested to remain in your room with the door closed until you are released from isolation by the radiation safety officer. This is usually one or more days after you have taken the medication. This can be a great time to get caught up on things such as reading magazines or talking to friends and family on the telephone. Please remember to bring diversional activities with you to the hospital. There is a TV available. You may bring your glasses, but do not bring items such as a laptop computer, which may become contaminated and have to stay in the hospital.
What about Visitors?
It is strongly advised that there be no visitors for the first 24 hours following radiation. We encourage you to use the telephone to communicate with your friends and family. If you receive visitors, a maximum visit of 30 minutes is allowed only. Visitors must wear gloves, protective shoe covers and a gown before entering the room. The amount of space between your visitor and you must be a maximum. This means your visitor must sit at the entrance of the door with you at the other end of the room. At the end of the visit, your visitor must dispose the gloves and shoe covers in the garbage located in the room and place the gown in the hamper. Visitors may not use your washroom or eat or drink any of your food. Pregnant women and children under the age of 18 may not visit during your hospital stay.
How Should I Communicate with my Nurse?
Although your nurse will spend very little time in your room, you can communicate frequently with your nurse by using the telephone and/or the intercom. Your nurse will also check in with you frequently by telephone or intercom to assess how you are doing.
What Should I Wear in the Hospital?
Please wear a hospital gown during your hospital stay and hospital slippers to avoid any contamination of your own clothes by perspiration. Your mattress and pillow will becovered with plastic. Please do not remove these coverings during your hospital stay.
What about Cleaning my Room?
You will be asked to make your own bed, if necessary. Dispose all linen and garbage in plastic bags provided in your room. All cutlery and dishes are to be disposed in a plastic bag also. Rinsing the sink, faucets and tub after use will help keep the radiation contamination to a minimum.
How do I Order my Meals?
You will remain on the low iodine diet. There are no choices. You may order kosher, vegetarian, or diabetic diets.
What about my Medications. Can I still take them?
If you are on medication, please let your doctor know. If your doctor decides that you may continue to take your medication during your hospital stay, please bring enough with you for the duration of your stay. You may store the medication in your room and take when required.
Is there Anything Else I should Know?
Please flush the toilet two or three times after elimination and wash your hands. Remember the urine is one of the key systems that excretes the excess radiation.
"Just for the Men". Please sit to void (pass water) to prevent any splashing contamination of the surrounding area.
Showering two or three times a day and washing your hair will help remove the excreted radiation through perspiration. Extra towels will be provided for you. When getting out of the shower, make sure you have a towel on the floor to step on.
Sucking on sour candies for the first 24-48 hours after radioiodine therapy is recommended by some thyroid cancer specialists to help reduce excessive radiation to your salivary glands. They recommend taking candies every 15 minutes during the day, as well as several times at night.
Further information: A study conducted in Japan and published in early 2005 compared two different timings of starting lemon candy. One group of patients started candy an hour after the radioiodine. The other group waited 24 hours before starting the candy. Both groups were asked to take 1-2 candies every 2-3 hours during the daytime through the 5th day after the radioiodine. The group that waited 24 hours had fewer salivary side effects. The authors concluded that waiting for 24 hours was preferable. However, they also noted that the study had limitations. Among these were that it was not double blinded, was not controlled, and patients in the group waiting 24 hours “tended to be treated more intensively” for salivary side effects. (Nakada, K, et al. Journal of Nuclear Medicine, 46(2): 261-6, 2005).
Several ThyCa medical advisors sent comments about this study. They noted that it is a single study and that it needs verification, because it was “non-controlled and not randomized adequately.” Some recommended conducting a study that is randomized, that includes a no-treatment control group that takes no candy at all, and that measures both acute and chronic symptoms as well as radioiodine uptake and retention in the salivary glands.
The American Thyroid Association’s guidelines published in early 2006 said that “evidence is insufficient to recommend for or against” taking sour candy, or other approaches such as amifostine, drinking a lot of water, or using cholinergic agents.
Radioactive Iodine Treatment - Side Effects
Signs to Watch for in Case of Drug Reaction (Allergy)
What about when I go home from the hospital?
Last updated: October 14, 2012