Preparation before 131 iodine treatment for hyperthyroidism 1. Patients should stop taking drugs and foods that affect the uptake of 131 iodine by the thyroid gland, such as: iodine, thyroid hormones, anti-thyroid drugs, foods high in iodine (such as kelp, nori and various seafood), etc. 2. Determination of thyroid uptake rate of 131 iodine, effective half-loss period, thyroid ultrasound and thyroid imaging. 3. Routine physical examination, chest X-ray, electrocardiogram, blood and urine routine, electrolytes, liver function, serum FT3, FT4, T3, T4, TSH, antibodies, etc. 4. In severe cases and with comorbidities, the original disease or comorbidity should be controlled first and then treated after the disease is stabilized.