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Difficulty: MediumPharmacologic Interventions

A 31-year-old man is brought to the emergency department by his partner due to severe confusion, high fever, and intractable vomiting for the past 12 hours. The partner reports that the patient was diagnosed with Graves disease two years ago but has been nonadherent to all medications for the past three months. Temperature is 40.1°C (104.2°F), pulse is 155/min, blood pressure is 162/68 mm Hg, and respirations are 26/min. Physical examination reveals a profusely diaphoretic and delirious patient. A prominent fine tremor is noted in the upper extremities. Neck examination reveals a diffusely enlarged, non-tender thyroid gland with an audible bruit. Electrocardiography demonstrates sinus tachycardia.

Arrange the following pharmacologic interventions in the strictly required chronological sequence for the acute management of this patient's condition.

  1. 1Intravenous propranolol
  2. 2Oral propylthiouracil
  3. 3Potassium iodide solution

Answer

The correct sequence is intravenous propranolol, followed by oral propylthiouracil, followed by potassium iodide solution.
The management of thyroid storm requires a strict sequence of pharmacologic interventions to prevent exacerbating the condition. Intravenous propranolol is given first to rapidly control severe sympathetic symptoms (e.g., tachycardia, hyperpyrexia, agitation) and reduce peripheral conversion of T4 to T3. Next, a thionamide such as propylthiouracil (PTU) is administered to halt the synthesis of new thyroid hormone. Finally, an iodine solution (such as potassium iodide) is given to block the release of preformed thyroid hormone (the Wolff-Chaikoff effect). The iodine must be given at least one hour after the thionamide to ensure synthesis is completely blocked; otherwise, the iodine will serve as a substrate and worsen the hyperthyroidism.

Step-by-Step Solution

1
Administer intravenous propranolol
Rapid reduction in sympathetic overdrive and inhibition of peripheral T4 to T3 conversion
Immediate stabilization of cardiovascular status and control of adrenergic symptoms is the highest priority in thyroid storm.
2
Administer oral propylthiouracil (PTU)
Inhibition of thyroid peroxidase and blocking of new hormone synthesis
Synthesis of new thyroid hormone must be halted before exposing the hyperactive gland to a heavy iodine load.
3
Administer potassium iodide solution
Inhibition of preformed thyroid hormone release
Iodine must be given approximately 1 hour after PTU to prevent the iodine from being utilized as a substrate to produce more thyroid hormone.

Key Concept

Chronological pharmacologic sequence in the management of thyroid storm

Alternative Method

In patients with severe asthma or heart failure where non-selective beta-blockers like propranolol are contraindicated, alternative sympatholytic agents such as esmolol (cardioselective, short-acting) or diltiazem (calcium channel blocker) may be used as the first step.
Estimated Time:1m 0s
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Topics

Pharmacologic Interventions

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