Several key questions about hyperthyroidism in pregnancy Q1 What should pregnant women with hyperthyroidism pay attention to in terms of diet? Pregnant women with hyperthyroidism should consume more high-energy, high-protein, high-calcium, vitamin-rich foods, while limiting the intake of iodine and avoiding foods with high iodine such as kelp, sea fish, sea jelly skin and nori. While ensuring the nutrition of mother and child, prevent the aggravation of the disease. How to differentiate “transient thyrotoxicosis in pregnancy” from “Graves’ disease”? ”Gestational transient thyrotoxicosis (GTT), also known as HCG-related hyperthyroidism, occurs in 2 to 3% of pregnant women. It occurs mainly in early pregnancy and is caused by an increase in serum human chorionic gonadotropin (HCG) levels, which stimulates the TSH receptors on the surface of the thyroid gland and causes thyrotoxicosis (mild increase in FT4 or FT3 and a decrease in TSH levels), often accompanied by severe pregnancy vomiting. It is important to note that “GTT” is a transient physiological change in thyroid function that occurs in early pregnancy, with mild symptoms of hyperthyroidism, and usually does not require anti-thyroid medication. Once misdiagnosed and wrongly administered anti-thyroid medication, it is likely to lead to hypothyroidism, which can be harmful to the pregnant woman and her fetus. To avoid misdiagnosis and mistreatment, it is important to differentiate between the two. Generally speaking, most patients with Graves’ disease have a history of autoimmune thyroid disease, mainly presenting with symptoms of hyperthyroidism such as panic attacks, lethargy, excessive sweating, etc. They usually do not have severe vomiting, and most of them have diffuse enlargement of the thyroid gland and proptosis, and positive autoantibodies to the thyroid gland such as TRAb and TPOAb. If left untreated, hyperthyroidism will gradually worsen with the prolongation of pregnancy and will not resolve on its own. In contrast, “GTT” is mainly seen in early pregnancy and is characterized by severe nausea, vomiting and other gastrointestinal symptoms, while the symptoms of hyperthyroidism are relatively mild. Most of the changes in thyroid function are temporary and will gradually return to normal with the prolongation of pregnancy. Can I breastfeed while taking anti-thyroid drugs (ATD)? Traditionally, it was thought that mothers with hyperthyroidism could not breastfeed. However, many clinical studies in recent years have shown that it is safe for patients with hyperthyroidism to breastfeed after delivery on moderate doses (PTU < 300 J/day or MMI < 20 J/day) of ATD (either PTU or MMI). For safety reasons, it is recommended that patients take the medication immediately after breastfeeding and then breastfeed a second time four hours later so that the interval between breastfeeding and the last dose is at least 3 to 4 hours, when the concentration of the drug in the milk is already very low and has little effect on the baby. Can thyroid disease be inherited? Autoimmune thyroid disorders (such as toxic diffuse goiter and Hashimoto's thyroiditis) have a genetic predisposition. A parent with thyroid disease has an increased chance of having a child with thyroid disease, but it does not necessarily mean that the offspring will develop thyroid disease. Therefore, patients with thyroid disease and their children should be aware of the basics of thyroid disease and have their thyroid checked regularly as a precautionary measure.