A 32-year-old woman is brought to the emergency department by her husband due to confusion… — USMLE Step 2 CK

A 32-year-old woman is brought to the emergency department by her husband due to confusion, severe agitation, and palpitations. She has a history of hyperthyroidism but stopped taking her medications three months ago. On presentation, her temperature is $39.4^\circ\text{C}$ ( $103^\circ\text{F}$ ), blood pressure is $150/70\text{ mm Hg}$ , and heart rate is $148/\text{min}$ and irregular. Physical examination reveals a staring gaze, a diffusely enlarged and non-tender thyroid gland, and a fine tremor in both hands. An electrocardiogram shows atrial fibrillation with a rapid ventricular response. A clinical diagnosis of thyroid storm is made. Arrange the following interventions in the most appropriate chronological sequence for the management of this patient, from initial acute stabilization to definitive long-term therapy.

1Administer intravenous propranolol
2Administer propylthiouracil (PTU)
3Administer potassium iodide solution
4Perform radioactive iodine ablation

Answer

The correct sequence is: Administer intravenous propranolol, followed by propylthiouracil (PTU), followed by potassium iodide solution, and finally perform radioactive iodine ablation.

The management of thyroid storm follows a strict, mechanistic sequence. First, beta-blockers (e.g., propranolol) are given to immediately control severe adrenergic symptoms. Second, a thionamide (e.g., propylthiouracil) is given to block the synthesis of new thyroid hormone. Third, an iodine solution (e.g., potassium iodide) is given at least one hour later to block the release of preformed hormone. Finally, definitive therapies like radioactive iodine ablation are reserved for the outpatient setting once the patient is completely stabilized.

Step-by-Step Solution

Administer intravenous propranolol

Controls adrenergic tone

Reduces life-threatening tachycardia, agitation, and tremor while also partially decreasing peripheral T4 to T3 conversion.

Administer propylthiouracil (PTU)

Blocks new thyroid hormone synthesis

Inhibits thyroid peroxidase, halting the production of new hormone. This is a prerequisite before administering iodine.

Administer potassium iodide solution

Inhibits hormone release

Prevents the release of stored thyroid hormone via the Wolff-Chaikoff effect. Must be given >1 hour after PTU.

Perform radioactive iodine ablation

Provides definitive treatment

Administered in the outpatient setting weeks after the acute crisis has resolved and the patient is chemically euthyroid.

Key Concept

Thyroid storm requires a strict sequence of pharmacotherapy to control symptoms, block hormone synthesis, and block hormone release safely.

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