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Hyperthyroidism — MCCQE Part 1 MCQ

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ModeratePalpitationsHyperthyroidismMCCQE Part 1

A 62-year-old woman presents with weight loss, tremor, heat intolerance, and new palpitations. Pulse is irregularly irregular at 132/min; TSH is suppressed and free T4 is elevated. She has no chest pain and is haemodynamically stable. What is the most likely diagnosis?

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Correct answer: B — Thyrotoxicosis with atrial fibrillation

Weight loss, tremor, heat intolerance, suppressed TSH, elevated free T4, and irregularly irregular tachycardia are most consistent with thyrotoxicosis complicated by atrial fibrillation. Panic disorder can mimic palpitations but does not explain biochemical hyperthyroidism. Anaemia could cause tachycardia but would usually be regular and would not suppress TSH. WPW requires a characteristic ECG pattern rather than this endocrine syndrome.

Reference: Choosing Wisely Canada; Canadian thyroid disease resources