A 32-year-old woman, G1P0, at 8 weeks gestation, has a known history of hypothyroidism managed with levothyroxine. Her thyroid-stimulating hormone (TSH) level before pregnancy was well-controlled at 2.0 mIU/L. She asks about potential adjustments to her medication during pregnancy. What is the most appropriate recommendation regarding her levothyroxine dosage?

The correct answer to the question "A 32-year-old woman, G1P0, at 8 weeks gestation, has a known history of hypothyroidism managed with levothyroxine. Her thyroid-stimulating hormone (TSH) level before pregnancy was well-controlled at 2.0 mIU/L. She asks about potential adjustments to her medication during pregnancy. What is the most appropriate recommendation regarding her levothyroxine dosage?" is Option C: Increase the dose by approximately 25-50% and recheck TSH in 4-6 weeks.

The other options — A) Decrease the dose by 25% to avoid fetal hyperthyroidism, B) Maintain the current dose and recheck TSH in the third trimester, D) Switch from levothyroxine to propylthiouracil (PTU) — are incorrect for this USMLE Exam Prep question. As explained above: Thyroid hormone requirements increase significantly during pregnancy (often by 25-50%) due to increased thyroid-binding globulin and fetal demand. TSH should be monitored closely (every 4-6 weeks) an…