What are the treatments for pregnancy complicated with hyperthyroidism?

The thyroid gland is a relatively important endocrine organ in the human body. Abnormalities in the thyroid gland cause a typical disease called hyperthyroidism. Generally, women are more likely to suffer from hyperthyroidism. During a woman's pregnancy, hyperthyroidism may occur, which may lead to serious consequences such as premature birth or miscarriage. So, what are the treatments for pregnancy complicated by hyperthyroidism? Let’s take a closer look below.

(1) Antithyroid drugs mainly include propylthiouracil (PTU), methylthiouracil (MTU), tapazole (also known as mathimazole, MMI) and carbimazole. They can both pass through the placenta and affect the fetus, but the amounts they pass through the placenta vary. In my country, propylthiouracil (PTU) is the first choice. About 5% of side effects may occur, including drug rash, itching, drug fever, and nausea, which are generally rare. Neutropenia is the most serious complication. Check the total and classified peripheral blood leukocytes regularly. When neutropenia occurs (defined as the total neutrophil count <1000-1500/ml and the granulocytopenia standard <500/ml), take care to prevent infection. Other rare drug toxic effects, such as propylthiouracil (PTU) can cause liver damage and elevated transaminases, and methimazole (MMI) can cause cholestatic jaundice. For mild side effects, other ATD drugs may be used as replacements; for severe side effects, the drug needs to be discontinued and active liver protection treatment should be administered. Currently, most doctors no longer give thyroid supplements when giving pregnant women propylthiouracil (PTU).

The goal of ATD drug treatment is to normalize the hypermetabolism as quickly as possible, prevent maternal complications, and deliver normal newborns so that these newborns will grow and develop normally in the future without any physical or intellectual sequelae. We recommend the use of the minimum dose of ATD during pregnancy to maintain FT4 in the upper 1/3 of the normal range. ATD overdose can cause fetal hypothyroidism and thyroid enlargement.

When a pregnant woman is diagnosed with hyperthyroidism, she should be treated. If the pregnant woman has few or no symptoms, the serum free thyroid hormone value is only slightly elevated, and the TSH is low, she can be closely observed and no medication is needed for the time being. Treatment is initiated only when symptoms worsen or when thyroid function tests show an increase in hyperthyroidism. In some patients, hyperthyroidism may naturally improve as pregnancy progresses to the later stages. Hyperthyroidism often recurs after childbirth and should be followed up closely.

For pregnant women with hyperthyroidism, in addition to paying attention to the clinical symptoms of hyperthyroidism during prenatal examinations, doctors need to reasonably analyze and interpret thyroid function tests and appropriately adjust the ATD dose. They should also pay attention to maternal and fetal complications, such as miscarriage, premature birth, fetal growth retardation, and pregnancy-induced hypertension syndrome. Strengthen fetal monitoring, such as electronic fetal heart rate monitoring. When ATD treatment is started, follow-up visits and thyroid hormone tests are performed every 2 weeks. After the condition stabilizes, tests are performed every 4 weeks. In thyroid function tests, FT4 and FT4I normalize first, followed by FT3, while TSH remains low several weeks or even months after FT4 becomes normal. Therefore, FT4 and FT4I are equivalent. They are the best indicators for observing the effects of ATD and are used to adjust the ATD dosage. TSH should not be used as an indicator for adjusting the ATD dosage within 2 months of the start of treatment. When TSH is normal, it means that the ATD dosage is sufficient and the dosage should be reduced. Consider stopping the drug in late pregnancy.

(2) β-adrenergic blockers are used to control symptoms of hypermetabolism. For example, they are very effective for palpitations. They are usually used together with ATD for a maximum of several weeks until the symptoms disappear and then the drug is discontinued. Commonly used are propranolol and atenolol. Beta-adrenergic blockers are only used as basic treatment or in combination with iodine before thyroid surgery to prepare for surgery and prevent thyroid crisis after surgery. Long-term use of beta-adrenergic blockers can easily cause miscarriage in pregnant women and is not conducive to fetal growth.

Beta-blockers are used to treat tachycardia in patients with hyperthyroidism, but propranolol crosses the placenta and also passes through breast milk. Long-term use may cause fetal growth restriction and bradycardia, and have adverse effects on newborns.

The above is an introduction to the treatments for hyperthyroidism during pregnancy. I hope it will be helpful for women. There are many ways to treat pregnancy complicated by hyperthyroidism. The key is that each woman's situation is different, and the treatment methods required are different. It is best to go to a regular hospital, diagnose your condition clearly, and then take targeted measures for treatment.