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Difficulty: HardPharmacologic Interventions

A 34-year-old woman is brought to the emergency department by her husband due to severe agitation, confusion, and fever. She has a history of Graves disease but stopped taking her antithyroid medications three months ago. Her temperature is 39.4°C (103.0°F), blood pressure is 158/72 mmHg, and pulse is 152/min and irregular. Physical examination reveals a diffuse, non-tender goiter, marked diaphoresis, and a fine tremor. An electrocardiogram demonstrates atrial fibrillation with rapid ventricular response. A clinical diagnosis of thyroid storm is made. While multiple therapies are required for comprehensive management, they must be administered in a highly specific physiological sequence to prevent the paradoxical worsening of the thyrotoxicosis. Arrange the following pharmacologic interventions in the correct chronological order of administration.

  1. 1Administration of intravenous propranolol
  2. 2Administration of oral propylthiouracil
  3. 3Administration of oral saturated solution of potassium iodide (SSKI)
  4. 4Administration of oral cholestyramine

Answer

The correct sequence for the acute management of thyroid storm is initiating intravenous propranolol, followed by oral propylthiouracil, then oral saturated solution of potassium iodide (SSKI), and finally oral cholestyramine.
The correct sequence targets the pathophysiology of thyroid storm in order of immediate lethality and mechanistic dependency. Propranolol immediately blunts the potentially fatal peripheral adrenergic hyperstimulation. Next, propylthiouracil (PTU) is given to halt the production of new thyroid hormone. Potassium iodide is then administered strictly one hour after PTU to prevent the release of stored hormone; if given before PTU, the iodine acts as fuel for the overactive gland to synthesize even more hormone. Finally, cholestyramine is added to decrease enterohepatic recycling and clear existing circulating hormone.

Step-by-Step Solution

1
Establish immediate cardiovascular control.
Administer intravenous propranolol.
Reverses severe adrenergic manifestations (tachycardia, tremor, agitation) which are the most immediate life-threatening complications of thyroid storm.
2
Halt de novo thyroid hormone production.
Administer oral propylthiouracil.
Blocks thyroid peroxidase, halting the synthesis of new hormone. This is an absolute prerequisite before administering exogenous iodine.
3
Prevent the release of preformed thyroid hormone.
Administer oral saturated solution of potassium iodide (SSKI).
Induces the Wolff-Chaikoff effect to stop hormone release. It must strictly be given 1 hour after the thionamide to prevent the iodine from serving as a substrate for a massive surge in new hormone synthesis.
4
Enhance systemic hormone clearance.
Administer oral cholestyramine.
Binds thyroid hormone in the gastrointestinal tract to prevent enterohepatic recycling, acting as a supportive adjunctive therapy after initial stabilization.

Key Concept

The acute pharmacologic management of thyroid storm requires a strict sequence to avoid patient harm: beta-blockade for immediate cardiovascular stabilization, thionamides to block hormone synthesis, followed strictly 1 hour later by iodine to block hormone release, and finally adjunctive therapies like bile acid sequestrants to enhance clearance.
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Pharmacologic Interventions

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