A 28-year-old woman at 15 weeks gestation comes to the office for a routine follow-up appointment. A year ago the patient was diagnosed with Graves disease that subsequently was well controlled on methimazole, but she was switched to propylthiouracil when she became pregnant. The patient feels tired, has occasional palpitations, and gained no weight during the first trimester; she has no other chronic medical conditions. Her mother has hypothyroidism.
Blood pressure is 124/78 mm Hg and pulse is 90/min. The thyroid gland is diffusely enlarged and nearly twice the normal size, but there is no bruit or nodularity. No proptosis is present. The remainder of the physical examination is within normal limits.
Laboratory results are as follows:
Which of the following is the most appropriate next step in management of this patient?

Question

A 28-year-old woman at 15 weeks gestation comes to the office for a routine follow-up appointment.  A year ago the patient was diagnosed with Graves disease that subsequently was well controlled on methimazole, but she was switched to propylthiouracil when she became pregnant.  The patient feels tired, has occasional palpitations, and gained no weight during the first trimester; she has no other chronic medical conditions.  Her mother has hypothyroidism.
Blood pressure is 124/78 mm Hg and pulse is 90/min.  The thyroid gland is diffusely enlarged and nearly twice the normal size, but there is no bruit or nodularity.  No proptosis is present.  The remainder of the physical examination is within normal limits.
Laboratory results are as follows:
 Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_98a2_65c5_853d_9d328ca058b7_MD0002_00 During the first trimester of pregnancy, β-hCG stimulation of the thyroid gland causes transient hyperthyroidism. To mimic this physiology and avoid fetal hypothyroidism, the goal of hyperthyroidism management during pregnancy is maintenance of a mildly hyperthyroid state; patients with hyperthyroidism are monitored closely with thyroid function tests every 4 weeks. Patients with subclinical, asymptomatic, or mild hyperthyroidism due to Graves disease do not require treatment. In contrast, symptomatic patients with moderate to severe hyperthyroidism due to Graves disease are treated with thioamides (eg, propylthiouracil [PTU], methimazole). PTU is indicated during the first trimester as methimazole is associated with congenital defects (eg, aplasia cutis, tracheoesophageal fistula, choanal atresia). However, because PTU can cause severe hepatotoxicity, patients are switched to methimazole during the second and third trimesters (Choices B and C). Symptoms (eg, tachycardia, tremor) are controlled with a short course of beta blockers (eg, metoprolol); long-term treatment is associated with fetal growth restriction and is avoided. (Choice D) Thyrotropin receptor antibodies are typically measured in patients with Graves disease at 18-22 weeks gestation to predict the risk of fetal thyrotoxicosis and to determine the need for ultrasound monitoring of the fetal thyroid. (Choice E) Radioactive iodine therapy is contraindicated during pregnancy. Thyroidectomy is indicated for patients with contraindications to thioamides (eg, allergy, agranulocytosis). Educational objective: Pregnant patients with hyperthyroidism are maintained at a mildly hyperthyroid state to avoid fetal hypothyroidism. Propylthiouracil is preferred for moderate to severe hyperthyroidism during the first trimester; because propylthiouracil can cause hepatotoxicity, methimazole is preferred during the second and third trimesters. Radioactive iodine is contraindicated during pregnancy. __________ References: Effects of methimazole and propylthiouracil exposure during pregnancy on the risk of neonatal congenital malformations: a meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/28671971) Hyperthyroidism in pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/22922367)

A 28-Year-Old Woman at 15 Weeks Gestation Comes to the Office