Patients with hyperthyroidism who are unable to adhere to anti-hyperthyroid medication or who are allergic to anti-hyperthyroid medication, or those with recurrent recurrence of hyperthyroidism, or those with combined hyperthyroidism in pregnancy, or those with contraindications to surgery, can choose radioactive iodine 131 treatment. The principle of radioactive iodine treatment for hyperthyroidism is that: the thyroid gland has a highly selective iodine 131 uptake function, and the iodine 131 uptake function of the thyroid gland of hyperthyroidism is higher than that of the normal patient. The function of thyroid gland in hyperthyroidism is higher than that of normal people. Most of the iodine 131 is concentrated in the thyroid gland after oral intake, and the beta ray released by it has a range of only 2 millimeters in the thyroid gland, which is almost completely absorbed by the thyroid gland, and the absorbed energy can destroy the hyperfunctional thyroid gland tissues to achieve the therapeutic purpose, while there is no adverse effect on the peripheral tissues of the thyroid gland. Because the effect of Iodine 131 in treating hyperthyroidism is similar to that of surgery, it is called “bloodless surgery”. Iodine 131 treatment of hyperthyroidism has a history of more than 50 years, with 1.5 million cases treated worldwide and more than 100,000 cases in China. Due to its good efficacy, simplicity and safety, fewer complications, and low cost, more and more patients have made it their first choice of treatment for hyperthyroidism. In the most developed United States, nearly 80% of patients with hyperthyroidism are treated with nuclear iodine 131. Radiation iodine 131 treatment needs to be prohibited before iodine-containing foods and drugs for more than two weeks, and stop using anti-thyroid drugs for more than three days, iodine should be taken on an empty stomach. Iodine 131 should be taken orally on an empty stomach, and food should be taken two hours after taking iodine 131 so as not to affect the absorption. The dose of iodine 131 treatment can be given in full at one time or divided into two doses at intervals of 5-7 days. If the patient is not cured after the first iodine 131 treatment, a second or even multiple treatments can be carried out. In a small number of patients, if goiter and hyperthyroidism are still obvious after the first iodine 131 treatment, the interval of re-treatment can be shortened to 3 months. After radioactive iodine 131 treatment for hyperthyroidism, there may be: (1) common digestive reactions, such as anorexia, nausea, vomiting, etc. Usually 4-12 hours after the treatment. They usually start 4-12 hours after treatment, and can be improved and disappeared about 36 hours after symptomatic treatment and rest. ② Local reactions: mainly due to thyroid edema and radiation thyroiditis caused 7-10 days after iodine treatment. Patients have neck itching, pain, pressure, sore throat and other discomforts, often lasting several days or weeks. Generally, it will be alleviated after a few days and does not require special treatment. (iii) Radioactive salivary gland inflammation: dry mouth, bitter mouth, pain and swelling occur. Supplementation with adequate water, lemonade, hard and sour candies or chewing gum will promote the secretion of the salivary glands and reduce the production of the above symptoms. ④Radiation cystitis: Since radioactive iodine is mainly excreted in the urine through the kidneys, drinking more water can increase urinary excretion, which can reduce the occurrence of cystitis in addition to lowering the dose of radiation to the whole body. ⑤ Hypothyroidism (hypothyroidism for short): after iodine treatment, hypothyroidism can occur in a small number of patients, which can be divided into two categories: transient and permanent, and the latter needs to be given thyroxine tablets for lifelong replacement therapy. (6) Sometimes infiltrative proptosis can be aggravated: severe malignant proptosis, when progressive development, such as existing corneal edema or distension, limitation of extraocular muscle movement or loss of vision, etc., requires immediate orbital decompression surgery to maintain vision. To treat hyperthyroidism with iodine 131, the patient only needs to drink a small glass of cooled water containing iodine 131, and can be gradually cured within 3-6 months. the total effective rate is over 90% after one treatment, and the recurrence rate is only 1-4%, and the cost is not high, which is not only effective, but also simple, safe and economical. The main disadvantage of iodine 131 treatment of hyperthyroidism is that part of the patient may occur hypothyroidism, but as long as the timely examination and treatment, hypothyroidism can be restored or medication to maintain normal life and work. And in developed countries, the goal of iodine 131 for hyperthyroidism is hypothyroidism, and then oral thyroxine tablets for replacement therapy. Iodine 131 treatment of hyperthyroidism, most patients once effective, but a small number of patients (about 20%) need to repeat the treatment or switch to other methods of treatment.