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A 42-year-old woman with past medical history of hyperthyroidism who had radioactive iodine treatment 2 years prior now presents to the emergency department with high fever, sweating, and confusion. These symptoms were preceded by coughing, sore throat, and body aches for 3 days. Shortly after arriving at the hospital, the patient started to have a partial-onset seizure with secondary generalization leading to generalized tonic-clonic jerks for a duration of 30 seconds followed by a period of postictal confusion. Two hours later, the patient is admitted to the neurologic intensive care unit (ICU) with a working diagnosis of "rule out status epilepticus" and is being hooked up to continuous electroencephalography. The initial vital signs are as follows: blood pressure (BP) 190/104 mm Hg, heart rate (HR) 105 to 110 beats per minute (bpm) in sinus rhythm, temperature 38.8°C (102°F), and o2 saturation 98% in room air. On examination, the patient's eyes are closed and she is arousable to nonpainful tactile stimulation; she is lethargic and diaphoretic, with hyperpyrexia, sinus tachycardia, tachypnea, mild resting tremors, and delirium. The patient's family reports normal diet and adequate hydration up until she started feeling ill this morning. While being examined, the patient develops a narrow QRS-complex supraventricular tachycardia with HR of 120 bpm, which subsided with an intravenous (IV) esmolol drip at 50 μg/kg per minute, which was given without the typical 0.5 mg/kg loading dose.

Given this patient's past medical history significant for hyperthyroidism, a working diagnosis of thyroid storm is made, which was believed to be triggered by an upper respiratory viral infection.

Describe the syndrome, mechanism, and typical clinical features.

Thyroid Crisis

Also known as thyroid storm or thyrotoxic crisis, it is an uncommon, acute, life-threatening manifestation of hyperthyroidism. If treatment is delayed, mortality rate exceeds 90%. Even with prompt diagnosis and treatment, commonly reported mortality rates range from 20% to 30%.1, 2


Thyroid storm is secondary to excessive thyroid hormones leading to hypermetabolic states. Common etiologies including trauma, perioperative surgical trauma to the thyroid glands, severe infection and sepsis, diabetic ketoacidosis, anesthesia induction, drug induced (chemotherapy, nonsteroidal anti-inflammatory drugs [NSAIDS], etc.), and partially treated hyperthyroidism with radioactive iodine for people with known hyperthyroidism have been reported to trigger this illness. Multinodular goiter and thyroid tumor with hypersecretion of thyroid-stimulating hormone (TSH) have been associated with this illness. In children, thyroid storm typically occurs in the setting of Graves disease.

Clinical features

Clinical features include high fever/hyperpyrexia, diarrhea, diaphoresis, hypertension (although the patient may be hypotensive in the late stage with heart failure or shock), sinus tachycardia, both supraventricular (more common) and ventricular tachyarrhythmia, high-output heart failure, tremors, convulsions, delirium, and coma.

The patient suddenly develops supraventricular tachyarrhythmia with a rapid ventricular response of 160 bpm and ...

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