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Amiodarone-Induced Hypothyroidism — RACP Adult Medicine MCQ

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ModerateEndocrinologyAmiodarone-Induced HypothyroidismRACP Adult Medicine

A 60-year-old man on amiodarone for 2 years presents with fatigue, weight gain, and cold intolerance. TSH is 35 mU/L and free T4 is 8 pmol/L. Anti-TPO antibodies are positive. What is the most likely type of amiodarone-induced thyroid dysfunction?

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Correct answer: C — Amiodarone-induced hypothyroidism

Amiodarone-induced hypothyroidism (AIH) is more common in iodine-sufficient populations and in patients with pre-existing thyroid autoimmunity (positive anti-TPO). The excess iodine from amiodarone inhibits thyroid hormone synthesis (Wolff-Chaikoff effect). Treatment is levothyroxine; amiodarone can usually be continued if clinically necessary.

Reference: ETA – 2018 – Amiodarone and Thyroid Guidelines; eTG Endocrine 2024