A 33-year-old woman with known Graves' disease develops fever of 41°C, atrial fibrillation with rate 160/min, agitation, and diarrhoea following an episode of pneumonia. Which antithyroid drug is preferred as the initial thionamide in this setting?
- A Carbimazole
- B Propylthiouracil ✓
- C Lugol iodine given before any thionamide
- D Radioiodine ablation
Correct answer: B. Propylthiouracil
Explanation
Thyroid storm is treated with a beta-blocker, a thionamide, iodine given at least one hour after the thionamide, glucocorticoids, and supportive care. Propylthiouracil is preferred over methimazole/carbimazole in storm because, in addition to blocking hormone synthesis, it inhibits peripheral conversion of T4 to T3 through its effect on deiodinase activity. Radioiodine is contraindicated acutely since it can worsen thyrotoxicosis by releasing stored hormone.
Reference: Williams Textbook of Endocrinology, 14th ed.
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Written and medically reviewed by the StethoPrep medical team.