Myxedema coma

• Presentation: hypothermia, hypotension, hypoventilation, Δ MS (coma rare), hyponatremia, hypoglycemia; often precipitated by infxn or major cardiopulmonary or neurologic illness
• Treatment: supportive care most important. Slow metabolism of drugs can lead to coma. Correction of hypothyroidism takes time. Load 200-400 µg T4 IV, then 50–100 µg IV qd; b/c peripheral conversion impaired, may also give 5–20 µg T3 IV q8h if unstable w/ bradycardia and/or hypothermia (T3 more arrhythmogenic); must give empiric adrenal replacement therapy first as ↓ adrenal reserves in myxedema coma.