I. Preparation before treatment 1. In principle, it is required to avoid foods with high iodine content (seaweed and various seafood) and iodine-containing drugs for 1~2 months before 131 iodine treatment. 2. Under the guidance of a nuclear medicine physician, the patient should make adjustments to relevant medications (such as anti-thyroid drugs and other related medications) and necessary nuclear medicine examinations. 3. Patients should understand the precautions, efficacy, possible near-term reactions and long-term complications of 131 iodine treatment, and should sign an informed consent form. Precautions for taking 131 iodine 1. Fast for 2 hours before and after treatment. Individuals who have difficulty tolerating fasting can drink a small amount of sugar water, and drink more water on the day of taking the drug. Avoid vomiting within 24 hours of taking the medication to affect the treatment effect. 2.Do not embrace infants and children within 2 weeks after treatment, and do not keep urine in the house within 2~3 days of medication. 3.Do not eat iodine-containing food within 2 weeks after treatment, and try to eat less iodine-containing food and medicine within 6 months. 4. Do not rub the thyroid gland for 2 to 4 weeks after treatment, avoid mental stimulation, colds and infections, pay attention to rest and strengthen nutrition. Some patients may experience a transient exacerbation, which is a normal treatment reaction. If symptoms such as high fever, frequent vomiting and diarrhea occur, please visit our department or seek medical consultation at local hospitals for symptomatic treatment. 5.After taking the medicine, the effect will be obvious in 2-4 weeks, and the symptoms will basically disappear or be cured in 2-3 months. In order to better control your condition, please come to our department for regular review and timely adjustment of the adjuvant treatment plan. 6.Recommended review time: 2 weeks, 1 month, 2 months, 5 months, 8 months, 1 year, 2 years, 3 years after taking the drug, and every 3 years thereafter. 7. Female patients should use contraception within 6 months after taking the drug. 8.Serious patients or those with severe comorbidities are treated with 131 iodine by hospitalization.