There are two main types of drugs that replace thyroid function: one is thyroid tablets, which are extracted from the thyroid tissue of pigs and are cheap but contain more impurities and are cheaper. The other is levothyroxine tablets, which are synthesized through genetic engineering and are more commonly used clinically and are relatively expensive. Thyroxine tablets are hormonal drugs and overdose may cause accelerated heart rhythm and even heart failure. Use with caution in the elderly, in patients with cardiovascular disease, with myocardial ischemia or diabetes. When you start taking thyroxine tablets after surgery, you should take sufficient amount so that the thyroxine in your body quickly reaches or slightly exceeds the pre-operative level, i.e., to reach the symptoms of mild hyperthyroidism, and then gradually adjust the dosage until it meets your body’s needs. The exact dosage is subject to the decision of your treating physician. In general, the dose of thyroxine tablets should be adjusted once every 1 to 2 weeks. If the patient’s appetite improves, constipation disappears, abdominal distension is reduced and there are no symptoms of hyperthyroidism such as pallor, palpitations, excessive sweating and weakness, and the thyroid function is normal, then the dose can be taken as a maintenance dose and taken for a long time. The adjustment of dose for patients with thyroid cancer is mainly based on the level of TSH, which is generally controlled at a low level of 0.01 mIU/L (normal value 2-10 mIU/L, 2.0-7.3 mIU/L for men over 60 years old and 2.0-16.8 mIU/L for women over 60 years old) after taking the drug. Thereafter, patients should have their thyroid function rechecked every 3 months or 6 months in order to adjust the dose. If symptoms such as irritability, excessive sweating, abdominal pain, diarrhea, and significant weight loss occur during the course of medication, it may be due to excessive dose, and the thyroid function should be checked at the hospital and the dose should be reduced as appropriate.