I. 131 iodine treatment for hyperthyroidism only requires one dose. What is the reasoning? Many patients have written to us about their poor results and recurrent attacks after taking medication for several years, and their doctors have often explained that they should insist on taking medication for more than two years, so they are skeptical that 131 iodine therapy can cure them after only one dose. Our answer is true and not the least bit exaggerated. According to the statistics, the cure rate of hyperthyroidism treated with 131 iodine is more than 85%, and only a few patients need to be treated again because of the size of the thyroid gland or other factors that affect the absorption of the medication. It should be noted that it takes a period of time to restore normal thyroid function after taking the medication, and the effect of the medication lasts for a long time, usually 2 to 3 weeks after taking the medication. Thyroid cells have a special affinity for iodide, so after taking a certain amount of 131 iodine orally, it can be taken up and absorbed by thyroid tissue in large quantities. 131 iodine can release a kind of beta ray (99%) and gamma ray (1%) when it decays spontaneously. The effective radiation range (range) of β-rays is only 0.5-2 mm, which can selectively destroy the epithelium of thyroid vesicles without affecting the neighboring tissues, and therefore does not produce toxic side effects in other tissues or organs. When the thyroid tissue is irradiated for a long time, the gland is destroyed and gradually necrosed and replaced by non-functional connective tissue, thus reducing the secretory function of the thyroid gland and curing hyperthyroidism, similar to the purpose of subtotal thyroidectomy. Therefore, some people call 131 iodine treatment for hyperthyroidism as “internal thyroid surgery”. Many foreign patients have written to us asking where they can buy radioactive iodine, and whether they can buy it on their behalf or by mail. Radioactive iodine is a special kind of medicine, which is not available in general pharmacies. According to the relevant state regulations, general pharmacies cannot operate radioactive drugs either. They must be operated and used by nuclear pharmacies or nuclear medicine departments of hospitals with the common approval of public security, environmental protection, health epidemic prevention and pharmacy administration, etc. Moreover, there are many rules and regulations in the operation of medical nuclear pharmacies, such as not selling to units and individuals without radioactive drug use licenses casually. Therefore, radioactive drugs cannot be purchased casually. The use of radioactive iodine must be done in units and departments that are licensed to use radioactive drugs, usually in the nuclear medicine department of a hospital, and only those who are qualified as nuclear medicine doctors or technicians can operate them. This is why the general medical sector (such as township health centers) cannot provide this service. Patients receiving radioactive iodine treatment must receive the treatment in a designated place, which is why the drug cannot be mailed or taken away. Patients with hyperthyroidism receiving radioactive iodine treatment have strict indications, and the dosage and requirements for taking the drug are different for each individual. There are some preparations to be made before treatment and many precautions to be taken after using the drug, which must be applied under the guidance of a nuclear medicine physician. Therefore, for patients in certain remote areas, they should not expect this treatment to be delivered to their doorstep, but should take the initiative to go to a regular medical unit that has been officially approved to have a nuclear medicine department to receive consultation and treatment. 3. Will radioactive iodine treatment for hyperthyroidism affect fertility and offspring? Many people are particularly concerned about whether radioactive iodine treatment for hyperthyroidism will affect fertility. As mentioned above, the majority of the treated 131 iodine is taken up by the thyroid tissue and rarely stays in other tissues and organs, so it has no effect on male and female reproductive organs. Although the radiation damage from a single treatment is not as great as that from a single gastrointestinal fluoroscopy, many scholars have conducted more in-depth studies. It has been observed that in a few patients after 131 iodine treatment, there is a transient chromosomal variation, but it can gradually return to normal. For patients who are infertile due to endocrine disorders caused by hyperthyroidism, fertility can be restored after 131 iodine treatment with the improvement of hyperthyroidism. Therefore, according to the current scientific level, 131 iodine treatment for hyperthyroidism does not have any effect on fertility and heredity. In order to protect the health of the next generation and intergenerational children, it is necessary to include pregnancy as a contraindication to 131 iodine treatment. Can radioactive iodine treat hyperthyroidism? Some patients have written to us asking whether 131 iodine can cure hyperthyroidism. Protruding eyes are one of the important signs of hyperthyroidism, but not every patient with hyperthyroidism has them. Severe progressive proptosis can occur spontaneously or after thyroid surgery (subtotal excision), but less frequently after 131 iodine treatment. 131 iodine improves proptosis after treatment in most patients, but only in a few cases does it worsen. It is generally believed that 131 iodine causes a gradual decrease in thyroid function, so that thyrotropin or proptosis-producing substances in the pituitary gland do not increase suddenly. It should be noted that there are also cases of complications of proptosis or aggravation of proptosis after 131 iodine therapy, because the proptosis-producing substances are produced less and more slowly, so doctors cannot give optimistic guarantee on the final efficacy of hyperthyroidism proptosis patients before treatment. V. Can hypothyroidism occur after radioactive iodine treatment? Hypothyroidism (hypothyroidism for short) is a complication after 131 iodine treatment for hyperthyroidism. Hypothyroidism that occurs within one year after treatment is called early-onset hypothyroidism, and hypothyroidism that occurs after one year is called late-onset hypothyroidism. The incidence of early onset hypothyroidism is reported to be 2%-5%. Early onset hypothyroidism is usually temporary and can recover spontaneously. Late onset hypothyroidism is usually permanent, with a reported incidence of 2% to 5% in the first year and an increasing incidence of 2% to 3% each year as time goes on. One of the possible reasons for hypothyroidism is that the nucleus of thyroid epithelial cells is damaged by ionizing radiation, so that they cannot divide and regenerate, and the longer the time, the more hypothyroidism will occur. How to reduce the occurrence of hypothyroidism after 131 iodine treatment is still a problem that has yet to be solved. Low thyroid is not terrible, as long as the appropriate amount of thyroxine is supplemented, normal thyroid function can be maintained. Patients and doctors of hyperthyroidism in Western European countries are optimistic about hypothyroidism, they do not tolerate hyperthyroidism, but are indifferent to hypothyroidism. Some scholars believe that hypothyroidism is a natural history of hyperthyroidism that can occur after various treatments and is not unique to 131 iodine therapy.