The prevalence of thyroid cancer has been increasing worldwide in recent years. According to a report released by the American Cancer Society, the incidence of thyroid cancer increased by 2.09 times between 2001 and 2013, and the 2010 Korean Cancer Statistics Report showed that thyroid cancer rose to the top of the list of cancers. Thyroid cancer has become one of the most common malignant tumors in China, and in 2012, the Ministry of Health of China reported that thyroid cancer is the third most common malignant tumor in women. 2011 Beijing Health and Population Health Report showed that the prevalence of thyroid cancer has increased 225.2% in 9 years. The epidemiological analysis of head and neck malignancies in Shanghai showed that the number of thyroid cancer cases nearly doubled between 2005 and 2009, and the 2010 Shanghai Malignancy Report showed that thyroid cancer was the 5th most common malignancy among women. At present, the treatment of thyroid cancer is still mainly surgery, supplemented by endocrine TSH suppression therapy and radionuclide therapy after surgery. Today, we will mainly talk about endocrine TSH suppression therapy. The role of TSH inhibition therapy: The cell membrane of differentiated thyroid cancer expresses TSH receptors, and TSH stimulation can increase the expression of some thyroid-specific proteins (such as Tg, sodium-iodine community) and accelerate the cell growth rate. The side effects of TSH suppression therapy include subclinical hyperthyroidism, increased angina in patients with myocardial ischemia, increased risk of atrial fibrillation in elderly patients, and increased incidence of osteoporosis in postmenopausal women. Inadequate dosing affects lipid metabolism and cardiovascular disease progression. The most commonly used drug for TSH suppression therapy: levothyroxine tablets (trade name Eugenol, L-T4) is one of the most commonly used drugs for postoperative patients with differentiated thyroid cancer. Despite its widespread use, some patients and even doctors are still unable to fully grasp the proper use and dose adjustment of this drug, resulting in patients not receiving proper treatment and even developing pharmacogenic hyperthyroidism or pharmacogenic hypothyroidism. How to take Eugenol: For post-operative patients with differentiated thyroid cancer who do not need I131 therapy, they should start taking Eugenol on the first day after surgery, usually starting with 50μg/d, or half if the patient has cardiovascular risk, and review the thyroid function in the 4th-6th weeks and adjust the dosage of Eugenol according to the TSH result, increasing 25-50mg each time. Whenever there is a change in the dose of medication, it is necessary to wait for 4-6 weeks to recheck the thyroid function until the TSH standard is reached. Thereafter, thyroid function will be reviewed once every 3 months for 1 year after surgery, and 1-2 times a year for lifetime follow-up after 1 year of surgery. If the thyroid has been completely excised and I131 treatment is required after surgery, you cannot take or need to stop taking Eugenol before, and you need to take Eugenol after the treatment is completed. There are two reasons for this: TSH is suppressed after taking the drug, which affects the absorption of iodine; thyroxine tablets themselves are iodine-containing drugs. When taking Eugenol, you should also follow the following points: 1. Eugenol should be taken daily. 2. Missed doses: If you miss a dose, you can take twice the dose the next day. If you miss more than one day, you should insist on taking twice the dose for multiple days until you make up for the missed dose. 3, time: take 1 hour before breakfast, 3 hours after dinner (before bedtime), half an hour before breakfast, three kinds of taking time absorption efficiency is reduced in turn, half an hour before breakfast is the bottom line to adhere to. 4, affect the absorption: take with water only. Should take certain special drugs or food after sufficient time interval: 1 hour interval with vitamins, hypertension drugs, tonic; 2 hours interval with iron and calcium containing food or drugs; 4 hours interval with milk and legumes; 12 hours interval with anti-cholamine or lipid-lowering resin. Note: Eugenol is absorbed in the small intestine; the acidic pH of the stomach in the fasting state is more important for the absorption of the tablets in the small intestine, so it is important to assess the function of the gastrointestinal tract, such as HP-related gastritis, atrophic gastritis, and fat drainage, by taking more than the expected dose. After the disease is cured, thyroid function and levothyroxine dose need to be re-evaluated; optimal drug absorption 70-80%; eating affects absorption; soy products affect absorption; coffee affects absorption. 5.Replacement to other products, such as Retis, also levothyroxine sodium tablets, requires re-evaluation of TSH level. 6.If a patient with normal thyroid function has symptoms such as panic and palpitations and cannot tolerate them, try taking the daily medication in divided doses, usually once before breakfast and once after dinner. 7. Use of Eugenol during pregnancy: Because of the large impact of thyroid function on the fetus, low thyroid affects the intellectual development of the child, and in the first trimester of pregnancy, because the fetal thyroid function has not yet been established, its thyroid development is completely dependent on the thyroid hormones provided by the mother, therefore, the need for Eugenol increases at this stage of pregnancy, and post-operative thyroid cancer patients whose thyroid function is controlled to the standard before pregnancy, the dose of medication before and during pregnancy needs to be adjusted according to The dose of Eugenol should be adjusted according to TSH level in time. The dosage of Eugenol for premenopausal women is usually larger than that for men and postmenopausal women due to the higher circulating levels of thyroid hormone binding globulin. 9. Patients need different doses of thyroid hormone replacement under different physiological and pathological states. Especially with the slowing down of hormone metabolism with increasing age, the dosage of Eugenol should usually be reduced.