gynecology and obstetrics
Thyroid Disorders in Pregnancy
Graves disease
Maternal Etiology is monitored clinically and with free T4 and high-sensitivity thyroid-stimulating hormone (TSH) assays. Treatment of Graves disease varies. Usually, pregnant women are given the lowest possible dose of oralpropylthiouracil(50 to 100 mg every 8 hours). Therapeutic response occurs over 3 to 4 weeks; then the dose is changed if needed.Propylthiouracilcrosses the placenta and may cause goiter and hypothyroidism in the fetus. Simultaneous use of L-thyroxine or L-triiodothyronine is contraindicated because these hormones may mask the effects of excessivepropylthiouracilin pregnant women and result in hypothyroidism in the fetus.Methimazoleis an alternative topropylthiouracil. Graves disease commonly abates during the 3rd trimester, often allowing dose reduction or discontinuation of the medication. In centers with experienced thyroid surgeons, a 2nd-trimester thyroidectomy, although very uncommon, may be considered after medications restore euthyroidism. After thyroidectomy, women are given full replacement of L-thyroxine (0.15 to 0.2 mg orally once a day), beginning 24 hours later. Radioactive iodine (diagnostic or therapeutic) and iodide solutions are contraindicated during pregnancy because of adverse effects on the fetal thyroid gland. Beta-blockers are used only for thyroid storm or severe maternal symptoms. If pregnant women have or have had Graves disease, fetal hyperthyroidism may develop. Whether these women are clinically euthyroid, hyperthyroid, or hypothyroid, thyroid-stimulating immunoglobulins (Igs) and thyroid-blocking Igs (if present) cross the placenta. Fetal thyroid function reflects the relative fetal levels of these stimulating and blocking Igs. Hyperthyroidism can cause fetal tachycardia (>160 beats/min), growth restriction, and goiter; rarely, goiter leads to decreased fetal swallowing, polyhydramnios, and preterm labor. Ultrasonography is used to evaluate fetal growth, thyroid gland, and heart. 