This document discusses myxedema coma, a life-threatening complication of severe hypothyroidism. It can be precipitated by a stressful event in someone who is already hypothyroid. Primary symptoms include altered mental status, low body temperature, low blood pressure, slow heart rate, and hypoventilation. Treatment involves supportive care in the intensive care unit, treating hypothermia, hyponatremia, and providing thyroid hormone replacement through intravenous levothyroxine and possibly liothyronine, as well as hydrocortisone therapy.