Taking radioactive 131 iodine to treat hyperthyroidism is convenient to use, has a high one-time cure rate and low cost, and is popular among patients. However, there are some people who worry that radiation is harmful, can hurt people’s vitality, can cause infertility, etc. What are the facts? We should have a proper understanding of it. Hyperthyroidism (hyperthyroidism) is a very common endocrine disease with many causes and types, but the common feature is excessive secretion of thyroid hormones. The common symptoms of hyperthyroidism include panic attacks, rapid heartbeat, fear of heat, excessive sweating, irritability, fatigue, loss of weight, increased appetite, and increased stools. Some patients may also find themselves with thickening of the neck and protruding eyes. If the above symptoms and signs appear, you should go to the hospital for relevant examination in time. Patients suffering from hyperthyroidism need not panic, as the disease is completely curable. However, it is different from a cold or flu that will be cured within a few days, there is a process. At present, there are four kinds of treatment methods in common use: internal anti-hyperthyroidism medication; surgery; radioactive iodine treatment and Chinese herbal medicine treatment. Internal treatment refers to the use of anti-thyroid drugs, such as tabazol, hyperthyroidism, methylthioxypyrimethamine, propylthioxypyrimethamine, etc., which are used to inhibit the synthesis of thyroid hormone, and are effective and simple. The disadvantage of this treatment is that it is long, requiring at least one year of regular medication, and has a high relapse rate of up to 50% after discontinuation of medication. Surgery is the most effective treatment for toxic thyroid adenomas. If the adenoma is cleanly removed, there is usually no recurrence of hyperthyroidism in the future. The disadvantage is that it is, after all, a surgical procedure with certain risks and a high recurrence rate (30%), characterized by diffusely enlarged hyperthyroidism of the thyroid gland. The use of radioactive 131 iodine to treat hyperthyroidism is now recognized as an effective method in the world. When former U.S. President George W. Bush suffered from hyperthyroidism during his administration, he was finally treated with this method after consultation and discussion by many world-class authoritative medical experts, and received good results. Currently, it is included as the preferred method in some Western countries. Why is isotope therapy so effective? Radioactive 131 iodine has the same physiological and biochemical properties as stable iodine, and the thyroid gland tissue has the same high absorption and concentration capacity for it. A large amount of concentrated radioactive 131 iodine exposes the thyroid gland to radiation, destroys part of the thyroid tissue, reduces the production of thyroid hormones, and relieves or cures hyperthyroidism. 131 iodine is an unstable radionuclide that emits γ and β rays during decay, with β rays accounting for 99% of the therapeutic effect. Because of the short range of β-rays, 1 mm on average and 2.2 mm on the longest, they have little or no effect on the tissues and organs surrounding the thyroid gland. This shows that radioactive 131 iodine is a safe and easy way to treat hyperthyroidism. Who is suitable for radioactive iodine treatment for hyperthyroidism? It is generally accepted that radioactive iodine therapy is suitable for adult patients of both sexes. The treatment of women of childbearing age and children is a matter of debate. In the early days of using 131 iodine to treat hyperthyroidism, there were concerns about the risk of cancer and leukemia and congenital abnormalities in fetuses. After half a century of clinical practice, these fears have been eliminated. Statistics from more than 1 million patients at home and abroad show no increase in the incidence of leukemia or thyroid malignancies, no more than natural incidence of fetal malformations, and no effect on fertility and offspring development. It is now unanimously accepted that treatment with 131 iodine is contraindicated in patients with hyperthyroidism during pregnancy and lactation because it can cause hypothyroidism in the fetus or infant. Therefore, we believe that 131 iodine is a safe treatment for patients of all ages (including women of childbearing age and children), except for pregnant and lactating women. Treatment of hyperthyroidism with radioactive 131 iodine is usually performed in nuclear medicine departments. Most patients can have their disease controlled after treatment and can be cured with a single dose of the drug. A small number of patients require a second treatment. It takes more than 3 weeks after taking 131 iodine for the treatment to begin to take effect, and within 3 months the symptoms gradually improve, the thyroid tumor shrinks, and some patients’ proptosis can be reduced. For those who need a second treatment, it should be done after six months, preferably 8-10 months apart. Some patients with hyperthyroidism have protruding eyes, the cause of which is complex and may be related to certain immune disorders in the body. Some patients have been found to have a substance in their serum that is associated with the development of proptosis. Only a few cases of proptosis may be aggravated by 131 iodine treatment, and this should be properly understood. Only a few patients have early reactions within 2 weeks after taking 131 iodine, mainly nausea, vomiting, dizziness and weakness; a few patients have rash and itching, which are generally mild and can disappear on their own; some patients may have transient exacerbation of hyperthyroidism, which is usually temporary, and very few serious cases have to be hospitalized for observation. Late complications are mainly hypothyroidism, caused by insufficient synthesis and secretion or physiological effects of thyroid hormones. The transient hypothyroidism caused by 131 iodine treatment is mild and can disappear on its own after 6-9 months. Another type of hypothyroidism is permanent hypothyroidism, the incidence of which is reported in China to be 2%-5% in the first year, and increases by 2%-3% year by year as time goes on. Hypothyroidism is not scary, as long as the right amount of thyroxine is supplemented, normal thyroid function can be maintained. Some scholars believe that hypothyroidism is a natural history of hyperthyroidism, which can occur after various treatments and is not unique to 131 iodine treatment. In summary, several methods of treatment for hyperthyroidism have their own characteristics. Relatively speaking, radioactive 131 iodine treatment for hyperthyroidism has the advantages of wide range of adaptation, simple method, safety and effectiveness, less number of doses and high cure rate at one time.