Thyroid Storm vs. Myxedema Coma

Introduction

• Presenter: Eddie Watson
• Topic: Comparison and understanding of thyroid storm and myxedema coma
• Venue: ICU training/education series

Thyroid Function Review

• Thyroid Hormones: T4 (inactive), T3 (active)
  • T4 converts to T3
  • Highly bound to albumin (99%)
• Functions: Controls metabolism and hormone sensitivity

Thyroid Storm

• Definition: Severe form of hyperthyroidism leading to systemic decompensation
• Causes: Mostly undiagnosed or under-treated Graves' disease precipitated by illness, injury, or surgery
• Pathophysiology Theories:
  • Changes in thyroid hormone binding to albumin
  • Changes in thyroid hormone receptors
  • Exaggerated sympathetic response
• Symptoms:
  • High fever (>104°F)
  • Tachycardia, palpitations, arrhythmias
  • Altered respirations, tremors, delirium, stupor, coma
• Diagnosis: Based on clinical signs and symptoms, lab values (TSH, free T3, T4)
  • No specific diagnostic test
• Treatment:
  • Key Strategies:
    1. Inhibit thyroid hormone production
    2. Block release of thyroid hormone
    3. Antagonize peripheral effects of thyroid hormone
    4. Supportive care
    5. Treat precipitating cause
  • Medications:
    • Methimazole (Tapazole)
    • PTU (preferred despite liver risk)
  • Blocking Hormone Release:
    • Inorganic iodine (preferred), radiographic contrast, or lithium (for iodine allergy)
  • Antagonizing Peripheral Effects: Beta-blockers (propranolol preferred, also esmolol and atenolol)
  • Supportive Care: Stress dose steroids, cooling measures, fluid replacement

Myxedema Coma

• Definition: Life-threatening emergency of severe hypothyroidism
• Prevalence: More common in women and elderly
• Mortality Rate: 20-50%
• Causes: Hypothyroidism with precipitating stressor (infection, trauma, drugs like tranquilizers, barbiturates, narcotics, cold exposure)
• Symptoms:
  • Hypothermia (80-88°F), hypoventilation, hypotension, bradycardia, hyporeflexia, hyponatremia, generalized interstitial edema, depressed consciousness
• Diagnosis: Based on labs and symptoms (Thyroid function tests, CBC, CMP, ABG, cortisol level, blood cultures, diagnostic imaging for rule out other conditions)
• Treatment:
  • Key Strategies:
    1. Hormone replacement (controversy over T4 alone vs. T3 and T4)
    2. Correct fluid and electrolyte balance
    3. Supportive care
    4. Identify and treat cause
  • Hormone Replacement: T3 and T4
  • Correcting Fluid/Electrolytes: Fluids for hypotension, hypertonic saline for hyponatremia
  • Supportive Care: Intubation, mechanical ventilation, warming measures, glucose, stress dose steroids

Conclusion

• Key Points: Distinction in pathophysiology, symptoms, and treatment strategies between thyroid storm and myxedema coma
• Importance: Both conditions, though rare, are crucial to recognize and treat effectively in ICU settings
• Wrap-Up: Emphasis on the gravity of these conditions, diagnostics based on clinical presentation, and comprehensive treatment protocols
• Series End: Final lesson in endocrine system series

Actions: Check related content on heart failure and lab tube order of draw for further learning.

Thanks: Appreciation for engagement, likes, and comments.

Thank you for attending this session on critical care endocrinology.