As we all know, thyroid cancer is the most prevalent malignant tumor of the endocrine system. It has four main types: papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated carcinoma. Among them, papillary carcinoma and follicular carcinoma are the most common, and together they are called differentiated thyroid cancer, accounting for about 95% of all patients. In the past, patients with differentiated thyroid cancer were mainly treated by surgery and no further treatment was given after surgery, resulting in recurrence and metastasis in some patients. It was not until the 1950s that research discovered that suppressing thyroid stimulating hormone (TSH) levels through oral thyroxine could inhibit the growth of tumor cells and thus reduce the recurrence of thyroid tumors, and the drug levothyroxine was synthesized in 1954. Since then, TSH suppression therapy with oral thyroxine after surgery has been gaining attention, but there has been no standard for how much dose of thyroxine should be taken. For a long time, patients took supraphysiologic doses of thyroxine. In 1994, the American physician Mazzaferri et al. reported the results of a 30-year follow-up analysis of a large number of cases showing that surgery + isotope therapy + TSH suppression therapy significantly improved survival and reduced recurrence in patients with differentiated thyroid cancer. At that time, due to the relatively large number of advanced patients, TSH suppression to less than 0.1 mIU/L was indeed effective in reducing tumor recurrence and metastasis. Therefore, long-term supraphysiologic doses of TSH suppression became an important tool in the standardized treatment of differentiated thyroid cancer for quite a long period of time. With the increasing attention to thyroid tumors and routine screening, most patients are now detected and treated effectively at an early stage, whether supraphysiologic doses of thyroxine medication are still applicable; the side effects of long-term oral high-dose thyroxine such as osteoporosis and cardiac arrhythmias are also gradually being concerned. Therefore, as the disease spectrum changes, the strategy of TSH suppression therapy also needs to be changed. Therefore, both the “Guidelines for the Treatment of Thyroid Nodules and Differentiated Thyroid Cancer in China” published in 2012 and the 2015 edition of the “ATA Guidelines for the Treatment of Differentiated Thyroid Cancer in the United States” released yesterday, have been revised. Both of them have revised the postoperative TSH suppression treatment for thyroid cancer. For patients with different risk of recurrence, different levels of TSH suppressive therapy are explicitly provided, and the dose and duration of therapy are adjusted according to the patient’s physical condition and tolerance to thyroid medications. This revision has changed the past phenomenon of either not taking the medication or taking too much. We call this the dual risk management model, which simply means that patients are classified into low risk, intermediate risk and high risk types according to their tumor to determine the level of TSH suppression and thus the dose and duration of thyroxine dosing. Generally speaking, TSH suppression should be below 0.1 in high-risk patients, between 0.1 and 0.5 in intermediate-risk patients, and between 0.5 and 2 in low-risk patients. Patients are then fine-tuned according to their age, heart function and other tolerances to thyroid medications also divided into low-risk and intermediate-high-risk groups. Lifelong suppression is recommended for medium- and high-risk patients, while low-risk patients are suppressed for 5 to 10 years, after which the treatment is changed to replacement therapy. It is important to note that: 1) the specific dose and duration of treatment should first be consulted with a medical professional; 2) oral thyroxine should be taken on time and in full doses; synthetic levothyroxine preparations are more effective than biological preparations because of the constant drug concentration; 3) the recommended time and method of taking the drug should be followed in the drug instructions to avoid drug-food interactions that reduce drug absorption; 4) follow-up visits should be paid attention to The level of thyroid hormone and TSH should be monitored regularly, once a month during dose adjustment and once every 3-6 months thereafter to avoid side effects of drug overdose or underdose and to avoid affecting the therapeutic effect; 5. Of course, it is still necessary to adjust the dose of drugs under the guidance of a doctor.