Dx: Myxedema coma
Last updated: 03/03/2015
Myxedema coma typically presents as decreased mental status and hypothermia in a patient with either chronic, severe hypothyroidism or any form of hypothyroidism in the setting of a significant physiological stressor (infection, MI, sedative medications/opioids). Patients may also demonstrate hypotension, bradycardia, hypoventilation, hyponatremia, and hypoglycemia. The term “myxedema” refers to non-pitting edema that can be seen in the face, hands and lower extremities. This is secondary to mucin deposition in the skin. This deposition may also occur in the airway, necessitating intubation. Diagnosis is made by history and physical exam, and treatment with thyroid hormone replacement (both T4 and T3) and glucocorticoids (often, coexisting adrenal insufficiency can be observed) should be initiated as soon as possible: prior to the availability of the results of laboratory investigation. Major clues are a known history of hypothyroidism or the presence of a thyroidectomy scar. Serum TSH, free T4 and cortisol levels should be checked to confirm diagnosis. If the patient has primary hypothyroidism (majority of myxedema coma cases), TSH will be high and free T4 will be low. Normal/low TSH and low free T4 indicate secondary hypothyroidism (hypothalamic or pituitary dysfunction).
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