Iodine fasting is usually seen before iodine 131 treatment, and patients who eat more iodine-containing foods during the iodine fasting period may need to reschedule the test. Iodine is one of the raw materials for the synthesis of thyroid hormones, and iodine is prohibited before the thyroid iodine 131 test in order to allow the absorption of iodine 131 to achieve the best effect. If iodine-containing food is consumed at this time, then it is necessary to consider re-election of the time for the test in order to avoid affecting the effect of iodine 131 treatment; if iodine-containing food is consumed in a small amount, it may not need any special treatment. People who need to abstain from iodine and consume iodized food during the period of iodine abstinence can go to the hospital and ask the doctor to make a judgment and give a treatment plan.