❄️ Myxedema Coma

🔍 Definition:

Myxedema coma is a life-threatening complication of severe hypothyroidism, characterized by:

• Decompensated metabolic state
• Hypothermia, bradycardia, hypotension
• Altered mental status, and often multi-organ failure

Despite the name, coma is not always present — altered sensorium may vary from confusion to stupor to coma.

⚠️ Why It Matters in ICU:

• Rare but high mortality (30–60%)
• Often misdiagnosed as sepsis, stroke, or hypothermia
• Requires early recognition and aggressive therapy

🧬 Pathophysiology:

1. Severe deficiency of T3 and T4:
• ↓ cellular metabolism
• ↓ thermogenesis
• ↓ adrenergic tone

2. Multi-organ hypofunction:

• Cardiovascular: ↓ HR, ↓ CO → shock
• CNS: ↓ perfusion → coma
• Kidneys: ↓ GFR → hyponatremia
• Lungs: hypoventilation → CO₂ retention

🧨 Precipitating Factors:

🩺 Clinical Features:

💡 Myxedema coma should be suspected in elderly, winter-onset, unresponsive, bradycardic, hypothermic patient.

🧪 Laboratory Findings:

🧠 Differential Diagnosis:

• Sepsis
• Stroke
• Adrenal crisis
• Hypothermia
• Sedative overdose
• Uremic encephalopathy

🔎 Diagnosis:

• Clinical suspicion is key
• No single diagnostic score is universally accepted, but diagnosis is made in presence of:
• Known hypothyroidism or strong signs
• Hypothermia
• Altered mental status
• Bradycardia
• Precipitating event
• Biochemically low T4 with high TSH

💊 Management Strategy:

🟩 1. Supportive Care

• ICU admission, mechanical ventilation if needed
• Warm blankets (passive rewarming only — avoid aggressive rewarming)
• Vasopressors (norepinephrine) if hypotensive
• Correct hypoglycemia, hyponatremia, acidosis

🟨 2. Thyroid Hormone Replacement

📌 Preferred: IV levothyroxine (T4):

• Loading dose: 200–400 mcg IV
• Maintenance: 50–100 mcg IV daily

Optional: Add IV liothyronine (T3) (especially in coma)

• 10–20 mcg IV, then 10 mcg q8–12h

T3 acts faster but may precipitate arrhythmias; use cautiously in elderly/CAD.

🟦 3. Glucocorticoids

• Hydrocortisone 100 mg IV q8h
• Given empirically until adrenal insufficiency is ruled out (due to possibility of coexistent autoimmune adrenalitis)

🟥 4. Treat Precipitating Cause

• Empirical antibiotics until infection ruled out
• Hold CNS depressants

⚠️ Avoid:

• Overzealous rewarming → vasodilation and cardiovascular collapse
• Sedatives/narcotics
• Inadequate dosing or oral therapy in comatose patients

📉 Prognosis:

🧠 Mnemonic – “MYXEDEMA” (for features)

• M – Mental status altered (coma/confusion)
• Y – Yellow skin (carotenemia)
• X – eXtreme hypothermia
• E – Edema (non-pitting)
• D – Depression (CNS, mood)
• E – Electrolyte disturbances (Na+, glucose ↓)
• M – Myopathy, bradycardia
• A – Apnea, hypoventilation