Title
Instructions: Listen to the podcast episode available below, and then submit your answers to the multiple choice questions. You will review the answers and the material covered during your next Continuity Clinic Session.
Thyroid Disease in Pregnancy
A 28-year-old woman, gravida 1, resents at 16 weeks of gestation for a prenatal care appointment. She reports increasing constipation, fatigue, and hair loss. She has no history of thyroid disease. Her TSH is 5 mIU/L and free thyroxine level is 0.6 ng/dL. The best management option for this patient
Show Explanation
• Overt hypothyroidism complicates 1% of pregnancies. It is complicated by an increased TSH, decrease free T4. Symptoms include fatigue, constipation, hair loss, cold intolerance, dry skin, weight gain, brittle nails, and myalgias.
• Levothyroxine should be initiated for women who have hypothyroidism in pregnancy. The TSH levels should be assessed every 4-6 weeks and levothyroxine dose adjusted by 25-50mcg until the patient becomes functionally euthyroid based on TSH levels. Patients should take levothyroxine 30-60 minutes before breakfast and 2-3 hours before or after their prenatal vitmains, iron or calcium.
• One third of patients with hypothyroidism will require increased levothyroxine doses in pregnancy, likely resulting from the increase in thyroid-binding globulin as a result of high estrogen levels. In patients who have undergone radioiodine ablation or thyroidectomy, a 25% increase of T4 replacement may be anticipated.
• Untreated overt hypothyroidism can result in compromised fetal neuropsychological development and an increased risk of miscarriage, preeclampsia, preterm birth, placental abruption, and fetal demise. There is no evidence that treatment of subclinical hypothyroidism (elevated TSH and normal fT4 and T3) improves outcomes, so it does not require treatment.
• Routine screening for hypothyroidism is not recommended in pregnancy. Patients may be screened if they have a personal history of thyroid disease, associated symptoms, or illnesses associated with thyroid dysfunction, like type 1 diabetes.
A 33-year-old patient, gravida 2, para 2, presents to your office 5 months postpartum to show you her newborn and talk about her recent symptoms. She had diet-controlled gestational diabetes. She is breastfeeding. Since giving birth, she experiences heat intolerance, fatigue, and occasional palpitations. Her physical exam reveals a pulse of 110 bpm and a normal CBC. Her TSH is low, and her free thyroxine is mildly elevated. The next best step is
Show Explanation
• Postpartum thyroiditis typically presents 3-6 months after delivery in a patient who was euthyroid prior to pregnancy. It is characterized by autoimmune thyroid dysfunction, and prevalence is 1-22%. Risk factors include positive thyroid antibodies in the first trimester, the presence of other autoimmune disorders, and gestational diabetes.
• The classic form of postpartum thyroiditis causes thyrotoxicosis at 2-6 months after birth, followed by transient hypothyroidism, with a return to a euthyroid state at 12 months postpartum. It can also present as isolated hypothyroidism or isolated thyrotoxicosis.
• Propranolol or metoprolol for management of palpitations during the thyrotoxic phase is a safe option in women who are breastfeeding. TSH should be repeated in 4-8 weeks to assess for resolution or progression into a hypothyroid phase. During the hypothyroid phase, levothyroxine can be started for symptomatic patients and tapered after 12 months.
• Postpartum thyroiditis may recur in up to 70% of subsequent pregnancies, and 10-50% of patients with postpartum thyroiditis can develop permanent hypothyroidism during their lifetime. TSH should be checked annually.
• It is important to distinguish postpartum thyroiditis from Graves disease. Presentation at 6.5 months or later after delivery, as well as physical exam findings like goiter with bruit and ophthalmopathy, are more indicative of Graves disease.
A 24-year-old patient, gravida 1, presents at 26 weeks of gestation to your office reporting swelling in her neck, tachycardia, palpitations, and heat intolerance. She has no personal or family history of thyroid disease. Her blood pressure is 140/90 mmHg, and her heart rate is 104 beats per minute. Examination does not demonstrate ophthalmopathy, but you notice some fullness of her thyroid gland on the right. Her TSH is less than 0.02 mIU/L and her free thyroxine (T4) is high at 5.0 ng/dL. Her only medication is prenatal vitamins, and she has no other contributory medical history. The best next step in treatment for this patient is administration of
Show Explanation
• This patient has overt hyperthyroidism with typical symptoms of tachycardia, palpitations, heat intolerance, and a possible goiter. Additional symptoms can include weight loss, frequent bowel movements, nervousness, diaphoresis, and tremors.
• Graves disease accounts for 95% of hyperthyroidism. Assessment should include thyroid function tests, radioactive iodine uptake (although not during pregnancy), and thyrotropin antibodies. Other causes of hyperthyroidism include toxic adenoma, toxic multinodular goiter, iodine-induced hyperthyroidism, trophoblastic disease, thyroiditis (including medication use), or exogenous and ectopic hyperthyroidism.
• Maternal risks of hyperthyroidism include cardiac arrhythmia, congestive heart failure, osteoporosis, and thyroid storm. Pregnancy complications include risks of preterm delivery, preeclampsia, growth restriction, and fetal demise.
• Propylthiouracil and methimazole decrease synthesis of thyroid hormone by decreasing organification of iodine. Propylthiouracil has a rare risk of hepatotoxicity and methimazole has a risk aplasia cutis and esophageal or choanal atresia. To balance these risks, typically propylthiouracil is used in the first trimester with transition to methimazole in the second trimester. Propranolol can be used to treat tachycardia associated with hyperthyroidism.