Recently, when many hyperthyroidism patients consulted online and I recommended radioactive iodine-131 treatment, many of them questioned that this treatment option would cause hypothyroidism and they were afraid that they would need to take medication for life. In fact, radioactive iodine-131 therapy is currently the preferred treatment for hyperthyroidism in foreign countries, and is often used in large amounts, advocating a single cure or even a cure for hypothyroidism. If hypothyroidism is treated correctly and in a timely manner, it will not cause any harm to the body and only requires the right amount of thyroid hormones to maintain normal thyroid function. This is not much different from the daily energy needs of the human body, and will not affect life and work, the physiological processes of the human body, or fertility. In contrast, hyperthyroidism, as an autoimmune disease, often brings serious complications if not treated in time, such as white blood cell decline, liver function damage, heart disease, mental depression, some people will also have enlarged thyroid gland and protruding eyes, middle-aged and elderly people will cause osteoporosis and pain around the body, etc. Therefore, when hyperthyroidism patients choose the iodine-131 method of treatment, they do not need to worry too much about the possible occurrence of hypothyroidism as a result. Timely and complete cure of hyperthyroidism is the most important thing.