Thyroid Disorders USMLE Step 1 Practice Question
A 42-year-old woman presents with progressive fatigue, weight gain, cold intolerance, and constipation over three months. Vital signs show HR 52 bpm, BP 138/88 mmHg, temperature 36.2°C. Laboratory studies reveal TSH 8.5 mIU/L and free T4 0.7 ng/dL. Thyroid peroxidase antibodies are elevated at 245 IU/mL. She denies current medications including lithium or amiodarone. Physical examination reveals a firm, nontender, diffusely enlarged thyroid gland without discrete nodules. Which diagnosis best explains these findings?
Answer choices
- AThyroid lymphoma
- BGraves' disease
- CSecondary hypothyroidism from pituitary adenoma
- DCentral hypothyroidism
- EHashimoto's thyroiditisCorrect answer
- FIodine excess-induced hypothyroidism from Wolff-Chaikoff effect
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