In the management of thyroid storm, when should iodine be administered?

• A. Before antithyroid drug
• B. After antithyroid therapy
• C. Concurrent with antithyroid drug
• D. Not used

Answer: (B)

In thyroid storm, the goal is to rapidly reduce circulating thyroid hormone by both stopping production and blocking release. An antithyroid drug is started first to halt new hormone synthesis, and because propylthiouracil also blocks peripheral conversion of T4 to T3, it helps cut active hormone quickly. Iodine should then be given after the antithyroid drug has begun working (usually within about an hour) to acutely block the release of stored thyroid hormone and reduce glandvascularity. If iodine is given first, the thyroid may continue to synthesize hormone before the antithyroid drug takes effect, potentially worsening the crisis once the iodine’s effect wears off. So the optimal sequence is to administer iodine after starting antithyroid therapy.