Condition	Treatment	Treatment goal	Monitoring	Antepartum testing
Hyperthyroidism	Methimazole (Tapazole; preferred agent after first trimester), 10 to 40 mg per day orally in two divided doses	Serum free thyroxine in upper one-third of normal range2	Measurement of serum TSH and free thyroxine every two weeks until on stable medication dosage2,3	Weekly beginning at 32 to 34 weeks' gestation in women with poorly controlled hyperthyroidism; consider testing earlier or more frequently in patients with other indications for testing3,14,15
	Propylthiouracil, 100 to 450 mg per day orally in two divided doses
Hypothyroidism	Levothyroxine, 100 to 150 mcg per day orally 2	Serum TSH < 2.5 mIU per L2	Measurement of serum TSH at 4 to 6 weeks' gestation, then every 4 to 6 weeks until 20 weeks' gestation and on stable medication dosage, then again at 24 to 28 weeks' and 32 to 34 weeks' gestation2,16	Typically reserved for women with coexisting conditions or obstetric indications, and in patients with other indications for testing15