Iodine is a substance contained in natural sea salt and iodized table salt. Iodine naturally regulates the thyroid, helping the gland produce hormones. Iodine deficiency is relatively rare in the United States; as Americans generally consume a lot of salt and the US Recommended Daily Allowance is only 150 mcg, with 400 mcg present in a teaspoon of iodized salt. A diet that is low in iodine is utilized prior to particular tests of thyroid gland function in order to determine thyroid disease. It is also used during some treatments for thyroid cancer to prevent interference with the action of radioactive iodine.
Purpose
A low-iodine diet, generally less than 50 mcg per day, is used prior to a radioactive iodine test for the thyroid. According to the Thyroid Community, such a diet is used prior to a radioactive iodine scan. Such a scan is used to determine whether you have an underactive thyroid (hypothyroidism) or an overactive thyroid gland (hyperthyroidism) when blood tests are not enough. Also, the Thyroid Cancer Survivors' Association states that a low-iodine diet is required prior to radioactive iodine treatments for thyroid cancer.
Time Frame
When your endocrinologist orders a radioactive iodine screening, you are instructed to not eat any iodine-containing foods one to two weeks prior to the scan, according to the Thyroid Community. Radioactive iodine treatments for thyroid cancer are conducted to destroy any remaining tumors prior to thyroid surgery. The Thyroid Cancer Survivors' Association reports that radioactive iodine treatments for cancer are administered two months after surgery. Your doctor will also ask you to stop taking thyroid hormone replacement medications while on the diet.
Foods
The key to a low-iodine diet is to avoid table salt, sea salt and any packaged foods. Processed foods contain iodized salt. The Thyroid Cancer Survivors' Association recommends using non-iodized and Kosher salt that does not contain iodine. The Association also reports that seafood, soybeans, dairy products and whole eggs are off-limits. During this time, you cannot take multi-vitamins as these also contain iodine. The Thyroid Community recommends that you eat fresh fruits and vegetables, egg whites, non-processed meats, clear sodas, homemade breads and distilled water.
Effects
Depleting your body of iodine will help guarantee you more accurate results during a radioactive iodine thyroid scan. On the day of the test, you will ingest an iodine tablet. The Thyroid Cancer Survivors' Association explains that your thyroid gland will react to the iodine quickly, considering you will have been without iodine for a number of days. The way that the thyroid reacts to the iodine will help your doctor make a better diagnosis.
Considerations
The Thyroid Cancer Survivors' Association points out that there is a difference between a low-iodine and low-sodium diet. Iodized salt contains sodium chloride, which is present in table salt. A low-sodium diet is utilized to help reduce blood pressure and the chances of developing heart disease. The restrictions are different than those associated with a low-iodine diet. Salt itself is not restricted on a low-iodine diet, as long as it is not sea salt or iodized salt.
