For individual patients, the L-T4 dose of suppressive therapy is the dose required to achieve their TSH suppression goal. In patients with DTC who have cleared all of their thyroid, the L-T4 dose for suppression therapy is usually higher than the replacement dose alone, averaging about 1.5-2.5 μg/kg/d. In older patients (especially those aged 80 years or older), the L-T4 dose to achieve TSH suppression is 20%-30% lower than in younger patients because the reduction in peripheral degradation of thyroid hormone in the elderly is greater than the oral absorption rate. decreases. The starting dose of L-T4 (eugenol) varies depending on the patient’s age and concomitant disease. The final dose of L-T4 is determined depends on the monitoring of serum TSH. During the L-T4 dose adjustment phase, TSH is measured every 4 weeks or so, and thyroid function is rechecked every 2-3 months for 1 year, every 3-6 months for 2 years, and every 6-12 months for 5 years after reaching the target to determine that TSH is maintained in the target range. The maintenance of stable TSH levels is best facilitated by taking L-T4 on an empty stomach before breakfast. If a dose is missed, double the dose should be taken until the entire missed dose is made up. Some patients will need to adjust their L-T4 dosage according to changes in TSH levels during winter and summer (winter increase and summer decrease). Certain special medications or foods should be taken at adequate intervals: 1 hour between vitamins and tonic products; 2 hours between iron and calcium containing foods or medications; 4 hours between milk and soy foods; 12 hours between cholestyramine or lipid-lowering resins. TSH can gradually reach a steady state about 4 weeks after each L-T4 dose adjustment (longer in older people). It is important not to stop the drug blindly during pregnancy. The optimal target value for TSH suppression therapy should be met: to reduce the recurrence, metastasis and associated mortality of DTC, but also to reduce the side effects and improve the quality of life caused by exogenous subclinical hyperthyroidism. To date, there is no consensus on this optimal target value. In recent years, there has been a shift in the philosophy of TSH suppression therapy, advocating the development of individualized treatment goals based on a dual risk assessment that takes into account both the risk of tumor recurrence and the risk of side effects of TSH suppression therapy in patients with DTC, moving away from a single criterion. Postoperative TSH suppression treatment goals for DTC patients based on dual risk assessment mU/L Risk of side effects of TSH suppression treatment Risk of recurrence of DTC Primary treatment (1 year after surgery) Follow-up period High risk Low risk High risk Low risk High risk High risk *<0.10.5#-1.00.1-0.5#1.0-2.0 (5-10 years) ***Low risk**<0.10.1-0.5#< 0.10.5#～2.0 (5-10 years) ****: Patients with high risk of side effects of TSH suppression therapy should have their TSH suppressed to the maximum tolerable level close to the standard and be evaluated dynamically while preventing and treating the corresponding lesions of the cardiovascular and skeletal systems; **: Patients with DTC with a high risk of recurrence and a low risk of side effects of TSH suppression therapy should be evaluated periodically. Patients with DTC with a high risk of recurrence and a low risk of side effects of TSH suppressive therapy should be evaluated periodically for cardiovascular and skeletal conditions;***: Thyroid hormone replacement therapy alone may be indicated after 5 to 10 years of disease-free survival;#: 0.5 mU/L in the table varies depending on the lower limit of the normal TSH reference range in each laboratory.