What are the diagnostic criteria for thyroid storm?

Diagnostic Criteria for Thyroid Storm

Thyroid storm is diagnosed using clinical criteria that include exaggerated signs and symptoms of thyrotoxicosis with evidence of multiorgan decompensation, usually occurring in the presence of an inciting trigger. 1

Clinical Presentation and Diagnostic Criteria

• Thyroid storm is characterized by severe acute exacerbation of the signs and symptoms of hyperthyroidism, representing a medical emergency 2
• Two established diagnostic scoring systems are commonly used:
  • Burch-Wartofsky Point Scale (BWPS)
  • Japan Thyroid Association (JTA) diagnostic criteria 1, 3

Key Clinical Features to Evaluate

• Thermoregulatory dysfunction: Fever is common, though some cases may present with normothermia 1, 4
• Cardiovascular manifestations: Tachycardia, hypertension, signs of congestive heart failure 1
• Gastrointestinal symptoms: Vomiting, diarrhea, hepatic dysfunction 1
• Central nervous system disturbances: Altered mental status, agitation, delirium 1, 5
• Multiorgan dysfunction: Can include lactic acidosis and liver dysfunction in severe cases 4

Laboratory Assessment

• Essential laboratory tests include:
  • Serum free triiodothyronine (FT3)
  • Free thyroxine (FT4)
  • Thyroid stimulating hormone (TSH) - typically low to undetectable (<0.01 mU/L) 6, 7
• Important note: Treatment should never be delayed while waiting for laboratory confirmation if thyroid storm is clinically suspected 6, 1
• Additional recommended tests:
  • Complete blood count - to evaluate for infection (potential trigger) and monitor for agranulocytosis during treatment 6
  • Thyroid peroxidase (TPO) antibody - helps distinguish between different causes of thyrotoxicosis 6
  • Liver function tests - to assess hepatic involvement 6, 4

Differential Diagnosis

• Several conditions can mimic thyroid storm and should be considered:
  • Sympathomimetic overdose
  • Substance use disorders
  • Alcohol withdrawal
  • Acute pulmonary edema
  • Heat stroke
  • Serotonin syndrome
  • Sepsis/septic shock 1

Special Considerations

• Pregnancy: In pregnant women with thyroid storm, the same diagnostic approach applies, with additional monitoring of fetal status 8, 6
• Atypical presentations: Be aware that some patients may present with normothermia or normotension, making diagnosis more challenging 4

Common Pitfalls to Avoid

• Delayed diagnosis: The key to diagnosis is considering the disease in patients with appropriate clinical features 1
• Waiting for laboratory confirmation: Treatment should be initiated based on clinical suspicion while awaiting laboratory results 6, 1
• Missing the precipitating factor: Always search for and address the trigger (infection, surgery, iodine exposure, etc.) 5, 3

Mortality Risk

• Without treatment, mortality from thyroid storm ranges from 80-100%
• With appropriate treatment, mortality decreases to 10-50% 3

Remember that thyroid storm is a clinical diagnosis based primarily on the recognition of severe thyrotoxicosis with evidence of systemic decompensation, and prompt treatment is essential to reduce morbidity and mortality.