Thyroid Storm: Clinical Signs and Symptoms
Cardinal Diagnostic Triad
Thyroid storm is diagnosed based on three core features: hyperthermia, tachycardia disproportionate to the fever, and altered mental status. 1 This represents a severe acute exacerbation of hyperthyroidism, not simply hyperthyroidism itself, and constitutes a life-threatening endocrine emergency. 1, 2
Core Clinical Features
Fever and Hyperthermia
- Marked pyrexia is a key diagnostic feature, with fever being one of the defining characteristics of thyroid storm 1, 3
- The hyperthermia is typically severe and out of proportion to other clinical findings 1
Cardiovascular Manifestations
- Tachycardia that is excessive relative to the degree of fever present is a critical diagnostic criterion 1, 3
- Cardiac arrhythmias, particularly atrial fibrillation, are common 1, 3
- Signs of congestive heart failure may develop as part of multiorgan decompensation 2, 3
- Risk of maternal heart failure is particularly significant in pregnant patients 1
Neuropsychiatric Symptoms
- Altered mental status manifests as severe agitation, nervousness, restlessness, confusion, or seizures 1, 3, 4
- Progressive deterioration from agitation to delirium, then stupor and ultimately coma occurs if untreated 1, 5
- Thyroid storm should be considered in the differential diagnosis of any patient presenting with altered mental status 4
Gastrointestinal Symptoms
- Vomiting is a frequent presenting symptom 1, 2, 3
- Diarrhea commonly occurs 1, 2
- Hepatic dysfunction and even fulminant hepatic failure can develop as a rare but serious complication 2, 3
Precipitating Events
- An identifiable inciting event is typically present, such as surgery, infection, labor and delivery, or iodine contamination 1, 5
- Recent infections, including Epstein-Barr virus, can precipitate thyroid storm 3
- Radioiodine (I-131) treatment can serve as a trigger 5
Clinical Progression and Prognosis
- Untreated thyroid storm progresses to shock, stupor, and coma, representing a medical emergency with mortality rates up to 30% 1, 3
- The condition is characterized by exaggerated signs and symptoms of thyrotoxicosis with evidence of multiorgan decompensation 2
- Early recognition and treatment are paramount to survival 6
Critical Management Pitfall
Treatment should be initiated immediately based on clinical presentation without delaying for laboratory confirmation. 1 While serum-free T3, free T4, and TSH levels help confirm the diagnosis, therapy must not be postponed awaiting test results. 7 The key to diagnosis is considering the disease in the differential, as there is no single laboratory value that establishes the diagnosis. 2