Myxedema Coma

Myxedema coma is life-threatening decompensated hypothyroidism. The name is misleading: the patient does not need to be comatose. A patient who is newly confused, difficult to rouse, or progressively less responsive may already have this emergency. Thyroid hormone normally supports cellular energy use, heat generation, cardiovascular activity, and respiratory drive. When hormone levels become critically low, the body slows to the point that it cannot maintain temperature, ventilation, circulation, glucose balance, or sodium balance. A precipitating illness or event can push a person with severe longstanding hypothyroidism into sudden decompensation. The bedside pattern is more useful than the label: altered mental status, hypothermia, bradycardia, hypoventilation, and metabolic derangement. Treat this as a critical illness, not as uncomplicated hypothyroidism.