Amiodarone-induced thyrotoxicosis — SCE Endocrinology MCQ

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HardThyroidAmiodarone-induced thyrotoxicosisSCE Endocrinology

A 73-year-old man taking amiodarone for ventricular tachycardia develops weight loss and worsening tremor. TSH is <0.01 mU/L, free T4 is 51 pmol/L and interleukin-6 is raised. Doppler ultrasound shows low thyroid vascularity and there is no goitre. What is the most likely diagnosis?

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Correct answer: A — Type 2 amiodarone-induced thyrotoxicosis

Low vascularity and absent nodular goitre support destructive type 2 amiodarone-induced thyrotoxicosis. Type 1 disease is iodine-induced hormone synthesis, usually in nodular goitre or latent Graves' disease with increased vascularity. The pearl is that amiodarone thyrotoxicosis classification guides thionamide versus glucocorticoid emphasis.

Reference: European Thyroid Association amiodarone thyroid dysfunction guideline