A 27-year-old woman, gravida 1 para 0, at 8 weeks gestation comes to the office due to nausea, dizziness, and heartburn. The nausea started at the beginning of the pregnancy and has increased over the last 3 weeks. The patient has had no vomiting, abdominal pain, or diarrhea. She has gained 1.5 kg (3.3 lb) during the pregnancy. Medical conditions include type 1 diabetes mellitus and hypothyroidism. Medications include an insulin pump, levothyroxine, and a daily prenatal vitamin. The dose of levothyroxine has not been changed in over 2 years. The patient's diabetes mellitus is well controlled; the most recent hemoglobin A1c was 6.4%. Her sister has type 1 diabetes mellitus and Graves disease, and her mother has hypothyroidism.
Blood pressure is 110/80 mm Hg, pulse is 94/min, and respirations are 18/min. Examination shows no abnormalities.
Laboratory results are as follows:
Which of the following is the best next step in management of this patient?

Question

A 27-year-old woman, gravida 1 para 0, at 8 weeks gestation comes to the office due to nausea, dizziness, and heartburn.  The nausea started at the beginning of the pregnancy and has increased over the last 3 weeks.  The patient has had no vomiting, abdominal pain, or diarrhea.  She has gained 1.5 kg (3.3 lb) during the pregnancy.  Medical conditions include type 1 diabetes mellitus and hypothyroidism.  Medications include an insulin pump, levothyroxine, and a daily prenatal vitamin.  The dose of levothyroxine has not been changed in over 2 years.  The patient's diabetes mellitus is well controlled; the most recent hemoglobin A1c was 6.4%.  Her sister has type 1 diabetes mellitus and Graves disease, and her mother has hypothyroidism.
Blood pressure is 110/80 mm Hg, pulse is 94/min, and respirations are 18/min.  Examination shows no abnormalities.
Laboratory results are as follows:
 Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_989f_cdb0_853d_21dd500e224a_MD0002_00 Thyroid hormone requirements increase during pregnancy due to increased metabolic demands. Concurrently, higher estrogen levels cause an increase in thyroxine-binding globulin (TBG). Patients with normal thyroid function can increase thyroid hormone production to saturate the increased number of thyroid hormone-binding sites on TBG, but patients with primary hypothyroidism are unable to increase thyroid hormone production. As a result, patients with primary hypothyroidism on levothyroxine therapy require an increase of about 25%-50% over their pre-pregnancy dose. Current guidelines advise that the dose of levothyroxine should be empirically increased by approximately 30% (eg, 2 additional levothyroxine doses weekly) at the time pregnancy is first detected (Choice E). Subsequently, TSH should be measured every 4 weeks and the dose adjusted to maintain TSH within trimester-specific norms (which are typically lower than nonpregnant reference ranges). Undertreated hypothyroidism increases the risk for maternal (eg, preeclampsia, placental abruption) and fetal (eg, preterm birth, fetal death) complications. (Choice A) The levothyroxine dose can be decreased in patients with TSH levels suppressed below the reference range, but this patient has a high TSH. (Choices C and D) T3 is made primarily by conversion from T4 in the peripheral tissues, and circulating levels in hypothyroid patients correlate poorly with thyroid status. If assessment of thyroid hormone is needed during pregnancy, free T4 (using trimester-specific norms) or total T4 can be measured. However, the dose of levothyroxine should be increased first, and TSH is usually adequate for monitoring of thyroid status. Educational objective: Pregnant patients with hypothyroidism should increase their levothyroxine dose at the time pregnancy is first detected. TSH should then be checked every 4 weeks and the dose adjusted to trimester-specific norms. __________ References: 2017 guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and the postpartum. (http://www.ncbi.nlm.nih.gov/pubmed/28056690) Practice bulletin no. 148: thyroid disease in pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/25798985) Hypothyroidism in pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/24622371)

A 27-Year-Old Woman, Gravida 1 Para 0, at 8 Weeks