A 31-year-old woman presents with fever, delirium, atrial fibrillation at 160/min, and a diffusely enlarged thyroid with an audible bruit. Temperature is 40°C. Free T4 is markedly elevated. After supportive care, which sequence of specific therapy is correct?
- A Iodine first, followed by carbimazole and propranolol
- B Propranolol, then propylthiouracil, then iodine one hour later ✓
- C Propylthiouracil alone, with beta blockers avoided due to heart failure risk
- D Radioactive iodine ablation as definitive emergency treatment
Correct answer: B. Propranolol, then propylthiouracil, then iodine one hour later
Explanation
Thyroid storm is treated with a beta blocker for adrenergic symptoms, then a thionamide (propylthiouracil preferred, as it also blocks peripheral T4 to T3 conversion), then inorganic iodide given at least one hour afterwards. Iodine given before the thionamide provides substrate and worsens hormone synthesis, which kills option A. Radioactive iodine is absolutely contraindicated in storm, and beta blockade remains indicated despite tachyarrhythmia unless there is decompensated heart failure or asthma.
Reference: Williams Textbook of Endocrinology, 14th ed.
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Written and medically reviewed by the StethoPrep medical team.