Thyroid Storm vs. Myxedema Coma

Introduction

• Last lesson in the series on the endocrine system
• Presenter: Eddie Watson
• Focus: Thyroid Storm and Myxedema Coma
• Importance: Understanding critical care for ICU patients

Thyroid Gland Overview

• Releases T4, which converts to active T3
• T3 and T4 are extensively bound to albumin (~99%)
• Key roles:
  • Controls metabolism
  • Influences hormone sensitivity

Thyroid Storm (Thyrotoxic Crisis)

• Severe form of hyperthyroidism
• Causes:
  • Undiagnosed/under-treated Graves' disease
  • Trigger events (illness, injury, surgery)
  • Theories: changes in hormone binding, receptor changes, or exaggerated sympathetic response
• Symptoms:
  • High fever (>104°F)
  • Tachycardia, palpitations, arrhythmias
  • Altered respirations, tremors, delirium, stupor, coma
• Diagnosis:
  • No specific lab test; check TSH, free T3, and T4
  • Diagnosis based on hyperthyroid symptoms and lab values
• Treatment:
  • Inhibit hormone production: Anti-thyroid meds (Methimazole, PTU)
  • Block hormone release: Inorganic iodine (first line), radiographic contrast, lithium (if iodine allergy)
  • Antagonize peripheral effects: Beta-blockers (Propanolol preferred)
  • Supportive care: Stress dose steroids, cooling, fluid replacement
  • Treat precipitating cause

Myxedema Coma

• Severe form of hypothyroidism
• Causes:
  • Hypothyroidism with additional stressors (e.g., infection, trauma, certain drugs, cold exposure)
  • More common in women and elderly
• Symptoms:
  • Hypothermia (80-88°F)
  • Hypoventilation, hypotension, bradycardia
  • Hyporeflexia, hyponatremia
  • Generalized interstitial edema (diminished appearance)
  • Depressed consciousness due to increased CO2
• Diagnosis:
  • Based on labs (thyroid function tests, CBC, CMP, ABG, cortisol, blood cultures)
  • Diagnostic imaging to rule out other disorders
• Treatment:
  • Hormone replacement: Controversy over T4 vs. T3+T4
  • Correct fluid/electrolyte balance:
    • Fluids for hypotension
    • Hypertonic saline for hyponatremia
  • Supportive care:
    • Intubation and mechanical ventilation
    • Temporary pacing for symptomatic bradycardia
    • Warming with blankets or devices
    • Glucose and stress dose steroids
  • Treat precipitating cause

Conclusion

• Understanding differences and treatment for Thyroid Storm and Myxedema Coma is crucial
• Both rooted in thyroid hormone imbalances but have different symptoms and treatments
• Importance of recognizing and managing these conditions in ICU

Call to Action

• Subscribe for more critical care content
• Check out previous lessons on heart failure and lab tube order

Thank you for watching!