Not long ago, Ms. Pan, who lives in Longjin Road, Guangzhou City, came to our department, saying that she had been suffering from hyperthyroidism for more than 7 years and had recurrent attacks, but after taking our “potion” only once, she has completely recovered and expressed her gratitude. What is the medicine that has such a good effect on hyperthyroidism? The so-called “potion” is a solution containing radioactive iodine (131I). 131I is an effective treatment for hyperthyroidism, and is popular among patients because of its simplicity, safety, short course of treatment, fast results, high one-time cure rate, low recurrence rate, and low cost. However, many patients do not understand this method or have a partial understanding of it. The following is a brief introduction of some basic knowledge about radioactive iodine treatment for hyperthyroidism for reference. Hyperthyroidism (hyperthyroidism) is a common disease, which is a clinical syndrome caused by excessive secretion of thyroid hormones, resulting in increased excitability and hyper-metabolism in the nervous, circulatory and digestive systems of the body. The prevalence is about 1%, and it is more common in women, most often in the age group of 20-40 years. The etiology and pathogenesis of hyperthyroidism have not yet been fully understood. Some patients with hyperthyroidism may experience some conscious symptoms, such as panic, rapid heartbeat, fear of heat, excessive sweating, hyperphagia, increased stools, menstrual disorders, irritability, impatience, fatigue, and weight loss. If the above symptoms and signs appear, it is likely that you are suffering from hyperthyroidism, and you should go to the hospital in time to have relevant examinations to make a clear diagnosis. Don’t worry about hyperthyroidism, it is completely curable. At present, there are four kinds of treatment methods in common use: internal anti-hyperthyroidism medication, surgery, radioactive iodine treatment and traditional Chinese medicine. The use of radioactive iodine treatment is currently recognized as an effective method worldwide and has been included as the first choice in many Western countries. Why is 131I effective in treating hyperthyroidism? Radioactive iodine and stable iodine have the same physiological and biochemical properties, and the thyroid tissue also has a high absorption and concentration capacity for radioactive iodine. In patients with hyperthyroidism, the rate and amount of thyroid hormone synthesis increases and the ability to concentrate radioactive iodine is higher. The large amount of concentrated radioactive iodine emits beta rays that expose the thyroid gland to radiation, which partially destroys the thyroid tissue and reduces the production of thyroid hormones, resulting in relief or cure of hyperthyroidism. Because beta radiation has a short range of 1 mm on average and 2.2 mm on maximum, it can destroy the thyroid tissue while having little or no effect on the surrounding tissues and organs of the thyroid. Therefore, radioactive iodine treatment for hyperthyroidism is safe and has few side effects. Who is suitable for radioactive iodine treatment for hyperthyroidism? It is generally accepted that all adult patients are suitable for 131I treatment. Early on, there were concerns about the risk of cancer, leukemia, and congenital abnormalities in the fetus due to 131I. After half a century of clinical practice, it has been proven that these concerns have been eliminated. According to the statistics of more than 1 million patients at home and abroad, no increase in the incidence of leukemia and thyroid malignancies has been found, and fetal malformations do not exceed the natural incidence and have no effect on fertility and offspring development. These have been extensively reported in the literature. The current expert consensus is that treatment with 131I is contraindicated in patients with hyperthyroidism during pregnancy and lactation because it can cause hypothyroidism in the fetus or infant. There is now controversy about the treatment of women of childbearing age and children. Treatment of hyperthyroidism with radioactive iodine is usually performed in a nuclear medicine department, where the doctor decides on the timing and dosage of 131I based on a comprehensive analysis of the patient’s symptoms, test results and other information. Most patients can be cured with a single dose of the drug, while a few patients require a second treatment. It takes more than 3 weeks after taking 131I to start the effect of treatment, and the symptoms gradually improve within 3 months, and all the symptoms are eliminated in 6 to 12 months. A small number of patients with hyperthyroidism may develop hypothyroidism after 131I treatment. It is caused by insufficient synthesis and secretion or physiological effect of thyroid hormones. The other is permanent hypothyroidism, the incidence of which is reported to be 2-5% in the first year and increases by 2-3% every year as time goes on. Low thyroid is not terrible, as long as the appropriate amount of thyroxine is supplemented under the guidance of a physician, 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 131I treatment. In conclusion, hyperthyroidism need not bother and radioactive iodine therapy can be preferred for most patients.