Emergency medical services arrive at the hospital with a 28-year-old female patient who is highly agitated and delirious. According to her family, she has a documented history of Graves disease but abandoned her prescribed medical therapy three months prior. Her temperature is 39.8°C (103.6°F), heart rate is 155/min, blood pressure is 160/70 mm Hg, and respiratory rate is 24/min. Physical examination reveals a diaphoretic patient with a diffusely enlarged, non-tender thyroid gland and a marked resting tremor. An electrocardiogram shows sinus tachycardia. Arrange the following pharmacologic interventions in the most appropriate chronological sequence for the acute management of this patient's condition.
- 1Intravenous propranolol
- 2Oral propylthiouracil
- 3Potassium iodide-iodine solution
- 4Oral cholestyramine
Answer
The correct chronological sequence is: Intravenous propranolol, followed by Oral propylthiouracil, then Potassium iodide-iodine solution, and finally Oral cholestyramine.
The correct chronological sequence targets the pathophysiology of thyroid storm safely and effectively. Intravenous propranolol is administered immediately to blunt the life-threatening adrenergic surge and decrease peripheral conversion of T4 to T3. Oral propylthiouracil is given next to inhibit thyroid peroxidase and halt de novo hormone synthesis. Potassium iodide is administered at least one hour after the thionamide; it leverages the Wolff-Chaikoff effect to block the release of preformed hormone. If iodine were given first, it would serve as substrate for new synthesis. Finally, oral cholestyramine is used adjunctively to bind excreted thyroid hormone in the gut.
Step-by-Step Solution
Key Concept
In the management of thyroid storm, severe adrenergic symptoms must be controlled first with a beta-blocker, followed by a thionamide to block new hormone synthesis, and then iodine (given at least 1 hour later) to block hormone release without providing substrate for new synthesis.