Signs and Symptoms of Thyroid Storm
Thyroid storm is diagnosed based on a combination of fever, tachycardia out of proportion to the fever, altered mental status (nervousness, restlessness, confusion, seizures), vomiting, diarrhea, and cardiac arrhythmia. 1
Cardinal Features
The diagnosis requires recognition of three core criteria 2:
- Hyperthermia (fever) 1, 2
- Tachycardia disproportionate to the fever 1
- Altered mental status with severe agitation, nervousness, restlessness, confusion, or seizures 1, 2
Cardiovascular Manifestations
- Cardiac arrhythmias 1
- Signs of congestive heart failure 3
- Tachycardia that is excessive relative to the degree of fever present 1
- Risk of maternal heart failure (particularly in pregnancy) 1
Gastrointestinal Symptoms
Neuropsychiatric Features
The altered mental status can manifest across a spectrum 1, 2:
- Nervousness and restlessness 1
- Confusion 1
- Seizures 1
- Severe agitation 2
- Slow mentation progressing to stupor and coma if untreated 1
Critical Context
Thyroid storm represents a severe acute exacerbation of hyperthyroidism signs and symptoms, not simply hyperthyroidism itself. 1 It is characterized by evidence of multiorgan decompensation 3.
Precipitating Events
An inciting event is typically identifiable 1:
Progression Without Treatment
Untreated thyroid storm progresses to shock, stupor, and coma. 1 This is a medical emergency with high morbidity and mortality 1, 3.
Clinical Pitfalls
Do not delay treatment waiting for laboratory confirmation. 1 While serum-free T3, free T4, and TSH levels help confirm the diagnosis, treatment should be initiated immediately based on clinical presentation 1. No single laboratory value establishes the diagnosis 3, 4.
The key diagnostic challenge is considering thyroid storm in the differential diagnosis when encountering a critically ill patient with the triad of fever, disproportionate tachycardia, and altered mental status 3. Important mimics include sympathomimetic overdose, alcohol withdrawal, septic shock, serotonin syndrome, and heat stroke 3.