Many studies have found that patients with thyroid cancer treated with TSH (thyroid stimulating hormone) inhibition with Eugenol or Raitis have lower recurrence rates and tumor-related mortality. TSH regulates thyroid-specific genes [thyroglobulin (Tg), thyroid peroxidase (TP0) and sodium-iodine transporter (NIs ), etc., and also regulate cell proliferation and differentiation, which is the theoretical basis of TSH inhibition therapy. However, the adverse effects of subclinical hyperthyroidism can occur with the use of eugenol for TSH suppression therapy, mainly: 1. it can cause osteoporosis and increase the risk of fracture; 2. long-term TSH suppression therapy can cause harm to the cardiovascular system of young and middle-aged patients, causing increased heart rate, enlarged left ventricle, increased mean arterial pressure and diastolic dysfunction; 3. The adverse effects of clinical hyperthyroidism are closely related to age. Although older patients have less severe symptoms of thyroid hormone overdose than younger patients, they are at higher risk of adverse reactions to TSH suppressive therapy. Elderly patients with endogenous and exogenous subclinical hyperthyroidism have a higher incidence of atrial fibrillation and cardiac hypertrophy compared to elderly patients with normal thyroid function. The 2009 American Thyroid Association (ATA) guidelines classify the risk of recurrence or death in patients after first surgery and I131 treatment into three groups of low, intermediate and high risk: 1. Characteristics of low risk group: no local and distant metastasis of tumor; total microscopic tumor resection; no local tissue and vascular infiltration, no invasive tumor 1. low-risk group characteristics: no local and distant metastases; complete microscopic tumor resection; no local tissue and vascular infiltration; tumor without aggressive histologic features (e.g., high-cell, insular, and columnar cell carcinoma); no iodine uptake foci outside the thyroid bed on the first whole-body scan after treatment if I131 therapy is administered. 2. intermediate-risk group (any of these): microscopic infiltration of soft tissues outside the thyroid; tumor with aggressive histologic features or vascular invasion. 3. high-risk group (any of these): microscopic tumor infiltration with incomplete tumor resection. distant metastases; iodine uptake foci outside the thyroid bed seen on the first whole body scan after I131 treatment. Therefore, the American Thyroid Association recommends: 1. initial postoperative treatment of patients in the high and moderate risk of recurrence groups: TSH suppression to <0.1 mu/L is recommended; 2. disease-free follow-up of patients in the high and moderate risk of recurrence groups: TSH suppression of 0.1 to O.5 mU/L is recommended; 3. initial treatment of patients in the low risk of recurrence group: TSH suppression of O.1 to O.5 mU/L is recommended; and 4. For the disease-free follow-up period of patients in the low-risk group, it is recommended that TSH be suppressed at the lower limit of normal value of O.5 mU/L.