Thyroid Disorders USMLE Step 1 Practice Question
A 45-year-old woman with Hashimoto thyroiditis on levothyroxine 100 mcg daily presents with recurrent symptoms of fatigue and cognitive impairment despite a TSH of 1.5 mIU/L (within normal range) and free T4 of 1.0 ng/dL (low-normal). She requests a trial of combination levothyroxine-liothyronine therapy. Which of the following best explains why this is NOT recommended?
Answer choices
- ALiothyronine has a short half-life requiring multiple daily doses and causes fluctuating T3 levelsCorrect answer
- BTSH-suppressive therapy with high-dose levothyroxine is superior to combination therapy
- CHer symptoms are pathognomonic for central hypothyroidism requiring thyrotropin-releasing hormone
- DLiothyronine increases the risk of Graves disease conversion
- ECombination therapy is contraindicated in patients over 40 years old
- FRandomized controlled trials have demonstrated that combination levothyroxine-liothyronine therapy worsens cognitive function compared to levothyroxine monotherapy
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