Amiodarone-induced thyrotoxicosis — SCE Endocrinology MCQ

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HardThyroidAmiodarone-induced thyrotoxicosisSCE Endocrinology

A 56-year-old man taking amiodarone develops weight loss and tremor. TSH is <0.01 mU/L and free T4 is 46 pmol/L. Thyroid ultrasound shows increased vascularity and positive TSH receptor antibodies. What is the most likely diagnosis?

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Correct answer: C — Amiodarone-induced thyrotoxicosis type 1

Underlying autoimmune or nodular thyroid disease with increased vascularity supports type 1 amiodarone-induced thyrotoxicosis, caused by iodine-induced hormone synthesis. Type 2 is destructive thyroiditis and often has reduced vascularity. Management often needs specialist input because amiodarone withdrawal may not be feasible.

Reference: European Thyroid Association Guidance; BNF