Endocrine Disorder Practice Test

In thyroid storm you want rapid control of hormone levels by first stopping new hormone production, then quickly blocking release of what’s already stored, while supporting peripheral effects. Propylthiouracil (PTU) does the crucial job of inhibiting thyroid hormone synthesis (and also decreases T4 to T3 conversion). Once synthesis is being blocked, giving iodide can promptly shut down the release of stored thyroid hormone. Because iodide can, in the absence of synthesis blockade, potentially sustain or increase hormone production in some scenarios, it’s given after PTU so that synthesis is already suppressed when iodide acts. Adding steroids helps reduce peripheral conversion of T4 to T3 and treats potential adrenal insufficiency, providing broad stabilization. So the preferred sequence is PTU first, followed by iodide, with steroids.