New-Onset Hypothyroidism Manifesting As Myxedema Coma: Fighting an Old Enemy.

Myxedema coma (MC) is a rare manifestation of severe hypothyroidism. This is a true endocrine emergency that may remain unrecognized. We present a case of a 49-year-old man who presented to the emergency department with generalized weakness and confusion. He was found to have low temperature, bradycardia, hypoxia, hypotension, glucose of 59 mg/dL, normal electrolytes, thyroid-stimulating hormone of 154 IU/mL, and free T4 of 0.1 ng/dL. His anti-peroxidase antibody level was 99 IU/mL. Echocardiography revealed a normal ejection fraction and no evidence of pericardial effusion. On the basis of his presentation and laboratory findings, he was diagnosed with MC, intubated, and admitted to the intensive care unit. Thyroid hormone replacement and glucocorticoid treatment were initiated immediately. After the clinical improvement, the patient was extubated. MC is associated with a high mortality rate and requires prompt recognition and treatment. This rare case reminds us that MC might still be the first manifestation of primary hypothyroidism, although considered an "old enemy".