TSH suppression therapy after surgery for DTC (differentiated thyroid cancer) refers to the use of thyroid hormones to suppress TSH at or below the low limit of normal or even undetectable levels after surgery, in order to replenish the thyroid hormone deficiency in DTC patients on the one hand, and to inhibit the growth of DTC cells on the other. The dose of thyroid hormone and the T3/T4 ratio in dry thyroid tablets are unstable and may bring about fluctuations in TSH, so they are not recommended as the first choice for long-term suppression therapy. TSH suppression levels are strongly associated with recurrence, metastasis, and cancer-related death in DTC, and this association is particularly clear for those with high-risk DTC. Cancer-related death and recurrence were increased with TSH > 2mU/ L. In patients with high-risk DTC, tumor recurrence and metastasis were significantly reduced when TSH was suppressed to < 0.1 mU/L after surgery. Postoperative TSH suppression of 0. 1 to 0. 5 mU/L in patients with low-risk DTC resulted in a significant improvement in overall prognosis, with no additional benefit when TSH was further suppressed to <0.1 mU/L. The growth and proliferation of some hypofractionated DTCs are not dependent on TSH, and in such patients, even suppression of TSH to very low levels may not slow progression. Prolonged use of supraphysiologic doses of thyroid hormone can result in subclinical hyperthyroidism. In particular, TSH needs to be maintained at very low levels (<0.1 mU/L) for a long time, which may affect the QOL (quality of life) of patients with DTC, increase cardiac load and myocardial ischemia (especially in the elderly), cause or aggravate cardiac rhythm disturbances (especially atrial fibrillation), lead to resting tachycardia, increased myocardial weight, increased mean arterial pressure, diastolic and/or systolic dysfunction, and even cause patients to The risk of hospitalization and death from cardiovascular disease-related events was increased. Many of these impairments can be reversed with a reduction in thyroxine dose. Another side effect of long-term TSH suppression is an increased incidence of osteoporosis (OP) in postmenopausal women, which may lead to an increased risk of fracture.