PTU Thyroid Storm — FRCA Primary MCQ

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HardPhysiology - Endocrine & MetabolicPTU Thyroid StormFRCA Primary

In thyroid storm, which thionamide also reduces peripheral conversion of T4 to T3?

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Correct answer: B — Propylthiouracil

The best answer is “Propylthiouracil”. Propylthiouracil inhibits thyroid hormone synthesis and also inhibits peripheral conversion of T4 to T3. Carbimazole inhibits synthesis but not this peripheral conversion; iodide inhibits hormone release after thionamide treatment, propranolol provides adrenergic control, and radioiodine is not acute thyroid-storm therapy.

Reference: RCoA, Primary FRCA Syllabus: https://rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf