1. What is the diagnosis of hyperthyroidism syndrome of pregnancy (SGH) and hyperthyroidism? SGH occurs in the first half of pregnancy (before 20 weeks) and is transient in nature, associated with increased production of hCG and over-stimulation of thyroid hormone production. It is characterized clinically by onset at 8-10 weeks, hypermetabolic symptoms such as palpitations, anxiety, excessive sweating, elevated serum FT4 and TT4, decreased or undetectable serum TSH, and negative thyroid autoantibodies. SGH is associated with severe pregnancy vomiting and occurs in 30-60% of patients with severe pregnancy vomiting. SGH needs to be differentiated from Graves’ disease hyperthyroidism, which is often associated with eye signs and positive thyroid autoantibodies such as TRAb and TPOAb. The diagnosis of hyperthyroidism can be established when serum TSH<0.1mIU/L and FT4>the upper limit of pregnancy-specific reference value exclude hyperthyroidism in pregnancy syndrome (SGH). 2. What is the management of hyperthyroidism syndrome in pregnancy? SGH is mainly treated with supportive therapy to correct dehydration and electrolyte disturbance. Vomiting needs to be controlled, dehydration needs to be corrected and water-electrolyte balance needs to be maintained in severe pregnancy vomiting. Anti-thyroid drug (ATD) therapy is not advocated because serum thyroid hormones can generally return to normal by 14 to 18 weeks of gestation. When it is difficult to identify SGH from Graves’ hyperthyroidism, ATD (e.g. propylthiouracil) can be used for a short time. Graves’ disease hyperthyroidism does not remit easily and requires further treatment with ATD. 3.How to choose medication to control hyperthyroidism that occurs during pregnancy? Women who have hyperthyroidism should preferably become pregnant after their thyroid function has been controlled to normal in order to reduce adverse pregnancy outcomes. There are two commonly used anti-thyroid drugs (ATD): methimazole (MMI) and propylthiouracil (PTU). To control hyperthyroidism in pregnancy, PTU is preferred in early pregnancy, with MMI as a second-line option. For the control of hyperthyroidism in pregnancy, the combination of ATD and L-T4 is not recommended. The equivalent dose ratio of PTU to MMI is 10:1 to 15:1 (i.e., PTU 100 mg = MMI 7.5-10 mg), and the starting dose of ATD depends on the severity of symptoms and serum thyroid hormone levels. In general, the starting dose of ATD is as follows: MMI 5-15mg/day or PTU 50-300mg/day in daily divided doses. Changes in thyroid function and adverse drug reactions (especially blood and liver function) should be monitored at the time of PTU and MMI conversion. Beta-adrenergic receptor blockers, propranolol 20-30mg/day every 6-8 hours, are helpful in controlling hyperthyroidism hypermetabolic symptoms. Application of long-term treatment with beta-blockers is associated with intrauterine growth restriction, fetal bradycardia and neonatal hypoglycemia, the use of which should be weighed against the advantages and disadvantages, and long-term use should be avoided. 4. What are the goals of hyperthyroidism control during pregnancy? Anti-thyroid drugs can cross the placental barrier. In order to avoid adverse effects on the fetus, the control goal should be achieved with the lowest dose of ATD, i.e., a maternal serum FT4 value close to or mildly above the upper reference value. In women treated with ATD, FT4 and TSH should be monitored every 2 to 6 weeks. 5.Can surgical treatment be used for hyperthyroidism during pregnancy? In principle, surgical treatment of hyperthyroidism during pregnancy is not recommended. The indications for thyroidectomy for hyperthyroidism during pregnancy are allergy to ATD; high dose of ATD is required to control hyperthyroidism; and the patient is not compliant with ATD therapy. If really needed, the best time to choose for thyroidectomy is the second half of the second trimester (14-27+6 weeks). Maternal TRAb titers are measured at the time of surgery to assess the potential risk of fetal hyperthyroidism. Preoperative preparation with beta-blockers and short-term potassium iodide solution (50-100 mg/day) is recommended.