A 62-year-old man on long-term amiodarone develops weight loss, tremor, and atrial fibrillation with rapid ventricular response. Free T4 is elevated, TSH suppressed, and color flow Doppler of the thyroid shows markedly reduced vascularity. Interleukin-6 level is high. Which treatment is most appropriate?

• A Carbimazole as monotherapy
• B Radioactive iodine ablation
• C Potassium perchlorate alone
• D Glucocorticoids such as prednisolone ✓

Explanation

Amiodarone-induced thyrotoxicosis type 2 is a destructive thyroiditis caused by direct cytotoxic drug effect, characterized by low glandular vascularity on Doppler and elevated interleukin-6, and it responds to glucocorticoids. Type 1, driven by excess iodine, shows normal or increased vascularity and needs thionamides. Radioactive iodine fails because iodine saturation suppresses uptake. The pattern here, low vascularity with high IL-6, points squarely to type 2 and steroid therapy.

Reference: Williams Textbook of Endocrinology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.