Myxedema coma.

Myxedema coma is a rare condition associated with high mortality. The pathophysiology is complex and often involves profound hypothyroidism as well as an inciting event. The diagnosis should be suspected based on the clinical presentation, and treatment should not be delayed while awaiting confirmatory laboratory data. In critically ill patients, laboratory differentiation between severe hypothyroidism and the euthyroid-sick syndromes is difficult and may require measurement of free hormone levels. Treatment consists of correction of electrolyte abnormalities, passive rewarming, treatment of infections, respiratory and hemodynamic support, administration of stress-dose glucocorticoids, and thyroid hormone replacement. Intravenous thyroxine, between 200 and 500 micrograms as the initial dose followed by 50 to 100 micrograms/day, is recommended. Concurrent therapy with triiodothyronine can also be considered.