Treatment of hyperthyroidism with radioactive iodine is usually performed in the nuclear medicine department. The nuclear medicine doctor decides the time and dosage of radioactive iodine based on a comprehensive analysis of the patient’s hyperthyroidism symptoms, clinical manifestations, laboratory test results, thyroid gland iodine absorption function and thyroid scan results. Generally speaking, after the diagnosis of hyperthyroidism is confirmed, some preparatory work should be done before treatment with iodine-131, such as controlling certain heavier complications and abstaining from iodine-containing foods or medications. Before and after taking iodine-131, some auxiliary therapeutic agents can be used according to clinical manifestations, and certain reactions should be noted for a period of time after taking the drug. Most of the patients can be controlled after treatment, and a cure can be achieved with a single dose. A small number of patients need a second treatment. After taking Iodine-131, it takes more than 2 weeks for the treatment to begin to take effect. Within 1-3 months, the symptoms gradually improve, the thyroid gland shrinks, and the disease recedes. In most patients, the symptoms are completely eliminated within 6 months to 1 year. If a second treatment is needed, it should be done after six months. Some patients with hyperthyroidism have protruding eyes, which is called proptosis. The causes are complex and may be related to certain immune disorders in the body, and some people have found that there is a substance in the serum of these patients that is related to the occurrence of proptosis, and the combined effect of various factors causes the increase and accumulation of tissue behind the eyes, the edema of intra-muscular fibrous tissue, and the infiltration of lymphocytes, which makes the eyes protrude. The occurrence and aggravation of proptosis are not parallel to the condition of hyperthyroidism. Most patients with hyperthyroidism will not have their proptosis aggravated by iodine-131 treatment, but only a few cases may have their proptosis aggravated. This should be properly understood. Hyperthyroid patients generally do not have any reaction after taking iodine-131, and only a few patients experience some side effects. Some reactions that occur within 2 weeks after taking the drug are called early reactions, mainly nausea, vomiting, dizziness, weakness, and in a few patients, rash and itching, which are generally mild and can disappear on their own. Some patients may experience transient exacerbation of hyperthyroidism, which is usually temporary, and very few patients with severe symptoms have to be hospitalized for observation. The main complication in the late stage is hypothyroidism (also known as hypothyroidism). It is caused by insufficient synthesis and secretion or physiological effect of thyroid hormones. One type of hypothyroidism caused by iodine-131 treatment is transient hypothyroidism, which is mild and can disappear on its own after 6 to 9 months, because of the recovery of incomplete thyroid cells damaged by radiation or compensatory proliferation of residual tissues. The other is permanent hypothyroidism, the incidence of which is reported to be 2-5% in the first year, and increases by 2-3% year by year as time goes on. Low thyroid is not terrible, as long as the right amount of thyroxine is supplemented, you can maintain normal thyroid function. Some scholars believe that hypothyroidism is a natural history of hyperthyroidism, which can occur after various treatments and is not unique to iodine-131 treatment. In summary, several methods of treating hyperthyroidism have their own characteristics, and it is necessary to develop the correct treatment plan for the individual patient. In contrast, radioactive iodine-131 treatment for hyperthyroidism is widely applicable, simple, safe and effective, with few doses, few complications, high cure rate and low cost, and can be the first choice for most patients. Recently, many people have raised some specific questions about radioactive iodine-131 treatment for hyperthyroidism, and the answers are as follows. 1. Radioactive iodine treatment for hyperthyroidism is usually performed in the outpatient department of nuclear medicine and does not require hospitalization. 2.Taking radioactive iodine must be done under the guidance of a nuclear medicine doctor, and the drug must not be taken away and cannot be mailed. 3. Before and after receiving radioactive iodine treatment, it is recommended to eat light and nutritious food, and to eat less seafood and iodine-containing food. 4. Women of childbearing age with hyperthyroidism can get pregnant six months after receiving radioactive iodine treatment. 5.Women with a history of hyperthyroidism who have improved after treatment and are asymptomatic and have normal laboratory tests do not need to take radioactive iodine. 6. Giant goiter without hyperthyroidism can also receive radioactive iodine treatment.