A 55-year-old man with persistent atrial fibrillation and a CHA₂DS₂-VASc score of 4 is started on anticoagulation. He is also started on amiodarone for rate/rhythm control. After 6 months, his TSH is suppressed to <0.01 mIU/L with elevated free T4 and T3. CT scan shows a vascular pattern on thyroid Doppler (type 2 amiodarone-induced thyrotoxicosis — AIT). The treatment of choice for type 2 AIT is:
- A Thionamides (carbimazole or PTU)
- B Radioiodine thyroid ablation
- C Discontinue amiodarone and observe without treatment
- D Oral prednisolone (40 mg/day with gradual taper) ✓
Explanation
Type 2 AIT is a destructive thyroiditis (amiodarone-induced lysosomal destabilisation causing follicular rupture) rather than iodine-induced hypersynthesis; it does not respond well to thionamides. Corticosteroids (prednisolone 40 mg/day with gradual taper over several months) are the treatment of choice, targeting the inflammatory destructive process. Type 1 AIT (iodine-induced, usually in underlying thyroid disease) responds to thionamides ± potassium perchlorate. Radioiodine is ineffective due to amiodarone-induced iodine overload reducing RAI uptake. Simply stopping amiodarone may not resolve thyrotoxicosis due to amiodarone's extremely long half-life (~40–55 days).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.