What is the recommended management for a patient with Graves' disease (GD) planning pregnancy?

Management of Graves' Disease in Patients Planning Pregnancy

For patients with Graves' disease planning pregnancy, propylthiouracil (PTU) should be used during the first trimester, followed by switching to methimazole for the second and third trimesters to minimize risks to both mother and fetus. 1, 2, 3

Pre-Conception Counseling

• Pre-conception counseling is essential for women with Graves' disease to optimize maternal and fetal outcomes 4
• TSH levels should be normalized (<2.5 mIU/L) before conception in women receiving levothyroxine after definitive treatment 4
• Discuss the risks of untreated hyperthyroidism during pregnancy, including increased risk of maternal heart failure, spontaneous abortion, preterm birth, and stillbirth 3
• Review treatment options before conception, as radioactive iodine is absolutely contraindicated during pregnancy 1

Treatment Options Before Pregnancy

• First-line therapy: Antithyroid medications with goal to maintain free T4 in high-normal range using lowest possible dose 1
• Second-line options: Consider definitive treatment before pregnancy if appropriate 5
  • Thyroidectomy may be preferred over radioactive iodine for women planning pregnancy soon, as TSH receptor antibodies remain elevated after radioiodine therapy 4
  • If radioactive iodine was used, pregnancy should be delayed for at least 4 months 1

Medication Management During Pregnancy

• First trimester: Propylthiouracil is preferred due to lower risk of specific congenital malformations compared to methimazole 2, 3
• Second and third trimesters: Switch to methimazole due to risk of maternal hepatotoxicity with continued PTU use 2, 3
• Monitor thyroid function every 2-4 weeks initially, then every 2-3 months once stable 1
• Goal is to maintain free T4 in the high-normal range using the lowest possible antithyroid drug dose 6
• Beta-blockers (e.g., propranolol) can be used temporarily for symptom control until antithyroid drugs take effect 6

Monitoring During Pregnancy

• Measure TSH and Free T4 levels every 2-4 weeks initially, then every 2-3 months once stable 1
• Monitor for side effects of antithyroid drugs, including agranulocytosis (sore throat, fever) and hepatitis 6
• Check TSH receptor antibody (TRAb) levels during pregnancy to assess risk of fetal/neonatal thyroid dysfunction 7
• Ultrasound monitoring for fetal growth and development, with special attention to fetal goiter if maternal disease is poorly controlled 6
• Low-dose aspirin (81 mg/day) should be prescribed by the end of the first trimester to reduce preeclampsia risk 6

Special Considerations

• Avoid radioactive iodine (I-131) during pregnancy and breastfeeding 6
• If thyroid storm occurs during pregnancy (rare but life-threatening), hospitalization and intensive treatment with multiple medications is required 6
• Monitor for hypertensive disorders, which are more common in pregnant women with thyroid disease 6
• Inform the newborn's physician about maternal Graves' disease due to risk of neonatal thyroid dysfunction 6

Postpartum Management

• Thyroid function should be closely monitored postpartum due to risk of relapse or exacerbation 4
• Breastfeeding is compatible with low-dose antithyroid medications 6
• Implement a contraceptive plan to prevent unplanned pregnancy while on antithyroid medications 6

Common Pitfalls to Avoid

• Failing to switch from PTU to methimazole after the first trimester 2, 3
• Using excessive doses of antithyroid drugs that can cause fetal hypothyroidism 5
• Not monitoring TRAb levels, which are crucial for assessing risk of fetal/neonatal thyroid dysfunction 8
• Discontinuing medications abruptly, which can lead to thyroid storm 6
• Not providing adequate contraceptive counseling to women on antithyroid medications 6