Thyroid Disorders USMLE Step 1 Practice Question
A 44-year-old woman presents to clinic with a 6-month history of progressive fatigue, difficulty concentrating, and cold intolerance. She reports a 3-kg weight gain despite no change in appetite. On examination, pulse is 52 bpm, blood pressure is 118/76 mmHg, and temperature is 36.2°C. Thyroid examination reveals a small, firm, non-tender gland without nodules. Laboratory studies show: TSH: 0.8 mIU/L (0.5-5.0)
Free T4: 0.6 ng/dL (0.8-1.8)
Thyroid peroxidase (TPO) antibody: positive (>35 IU/mL)
Thyroglobulin (Tg) antibody: positive (>40 IU/mL)
TSH-receptor antibody (TRAb): negative Which of the following is the most likely diagnosis?
Answer choices
- AHashimoto's thyroiditis with early hypothyroidism and autoimmune destructionCorrect answer
- BGraves' disease with TSH suppression from thyroid hormone excess
- CSecondary hypothyroidism from pituitary insufficiency
- DEuthyroid sick syndrome from chronic illness
- EThyroid hormone resistance syndrome with target tissue insensitivity
- FSubclinical hyperthyroidism with factitious ingestion of levothyroxine
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