Etiology: The etiology is unknown, it is an autoimmune disease and autoantibodies against thyroglobulin can be detected in the patient’s blood. Clinical manifestations: Most commonly seen in middle-aged women (95% of cases). The actual incidence of HT is much higher than the clinical diagnosis rate, and it is more common in women, 4-20 times more common than in men. gradually increases in size. In a few patients, the thyroid gland may enlarge rapidly, but rarely there is compression of the neck organs, leading to dyspnea and dysphagia. In the early stages, there is a lot of discomfort in the neck and the thyroid gland becomes enlarged and gradually becomes tougher and harder, which can be easily misdiagnosed as Ca. The course of the disease is 1-2 years. The enlarged thyroid gland is obviously thickened in the isthmus, but does not invade the peritoneum. The incidence of HT combined with cancer has been reported to be 5-22%, especially in patients with isolated nodules in the thyroid gland, and Off reported 146 cases of CLT with isolated cold nodules. HT with hypothyroidism: Long-term L-T4 replacement therapy is required ★ Generally start with a small dose, usually no more than 200µg/d Older patients or those with ischemic heart disease should preferably be treated with L-T4, starting with 25-50µg/d and gradually increasing the dose at intervals of 2-4 weeks or more ★ Pregnant patients should increase the dose of L-T4 by 25% to 50% HT with subclinical hypothyroidism: treatment as above. Generally, starting from small doses, L-T450-100µg/d treatment for 1 year, about 24% of patients can return to normal thyroid function HT thyroid function, such as asymptomatic, small thyroid gland, follow-up observation is not urgent treatment; goiter obvious, can be given L-T4 treatment