Hypothyroidism : Myxedema Coma

Case Synopsis

A 53-year-old woman with a long history of hypothyroidism and tobacco abuse presents to the emergency department with generalized weakness, lethargy, mild shortness of breath, edema of her lower extremities, constipation, and slow speech. She admits to stopping her thyroid replacement 2 years ago. Her current medication list includes only Flonase and Metamucil. Her physical examination is significant for hypothermia, lethargy, bradylalia, dry mucosa, brittle and coarse hair, distant heart tones, bradycardia, decreased breath sounds bilaterally, a distended but nontender abdomen, and bilateral lower extremity nonpitting edema. The laboratory results are notable for mild anemia (hemoglobin 9.4 g/dL), leukocytosis (white blood cell count 17.2 × 10 ⁹ /L), and hypokalemia (3.1 mM). The patient is profoundly hypothyroid with a thyroid-stimulating hormone (TSH) level of 120 mU/L (normal value 0.4–4.0 mU/L) and free T ₄ of 0.08 ng/dL (normal value 0.46–0.76 ng/dL). Chest, abdomen, and pelvic computed tomography images reveal a large pericardial effusion, small right pleural effusion, and marked ascites. The endocrinology consultant immediately starts the patient on intravenous (IV) levothyroxine, liothyronine, and hydrocortisone. The patient also requires a dopamine infusion secondary to persistent bradycardia and hemodynamic instability.

Because there were mild signs of early tamponade, a needle pericardiocentesis was completed, followed 3 days later by a pericardial window for the large recurrent pericardial effusion. The induction of anesthesia for the pericardial window was performed using a combination of glycopyrrolate 0.4 mg, hydrocortisone 100 mg, etomidate 20 mg, fentanyl 50 μg, and succinylcholine 120 mg. The initial intubation attempt was unsuccessful with a 7.5 endotracheal tube (ETT), probably due to the airway edema and mucosal swelling. Therefore a 6.5 ETT was passed into the trachea. An appropriate depth of anesthesia was achieved with only 0.4 minimum alveolar concentration (MAC) isoflurane, low-dose fentanyl, and intermittent cisatracurium. Her anesthetic course was significant for hypothermia and bradycardia. Thus the patient also required a total of 50 mg of IV ephedrine to maintain an appropriate heart rate. The trachea was extubated at the end of the procedure after a prolonged emergence. Levothyroxine was continued throughout her hospitalization, and hydrocortisone was gradually tapered over 2 weeks. The pericardial drain was maintained for 3 days during her intensive care unit stay. The patient was discharged from the hospital to a long-term care facility 14 days after admission.