Chapter 4 - Myxedema Coma

Abstract

Myxedema coma is a life-threatening endocrine emergency that reflects progression of inadequately treated profound underlying hypothyroidism into a comatose state. The incidence varies from 0.2 to 1.08 per million people per year, and it typically presents in a patient who develops an infection or other systemic disease superimposed upon previously undiagnosed, untreated, or inadequately treated hypothyroidism. The most frequent presentation is that of coma or an obnubilated mental status associated with bradycardia, hypothermia, hyponatremia, hypotension, gastric atony, hypercapnia, and/or hypoxemia. Diagnosis is mainly clinical and is based on the concomitant presence of typical signs and symptoms in the setting of a patient with suspected hypothyroidism. Scoring systems based on clinical evidence can be used as objective tools to suggest or confirm diagnosis. As soon as myxedema coma is suspected, the patient should be transferred to the intensive care unit for confirmation, close monitoring, and prompt treatment. Any delay in treatment initiation may contribute to an increased risk of mortality. Although various modifications in treatment have been proposed, the main pillars of therapy rely on thyroid hormone therapy, respiratory support, glucocorticoids (particularly when associated with adrenal insufficiency), hyponatremia correction, and conservation of body heat. Particular attention should be paid to elderly, more fragile patients, as aggressive thyroid hormone therapy may increase the risk of cardiovascular events. Despite having a high mortality rate, timely diagnosis and improved treatment protocols have largely contributed to improve survival in myxedema coma.