Attending Physician OhioHealth Riverside Methodist Hospital, United States
Introduction: Myxedema coma is a life-threatening complication of severe untreated hypothyroidism. Diagnosed clinically, it presents with a constellation of symptoms including altered mentation, hemodynamic instability, and hypothermia. Given its high mortality rate, prompt recognition and treatment are essential.
Description: A 19-year-old pregnant female (33 weeks gestation) presented with premature rupture of membranes. Medical history included primary adrenal insufficiency and hypothyroidism, complicated by medication non-adherence. She had not received prenatal care. The patient was hemodynamically stable, but minimally responsive. Studies revealed thyroid-stimulating hormone (TSH) of 94.4mcIU/mL (0.27-4.20mcIU/mL), total T3 86ng/dL (91-218ng/dL), total T4 3.6mcg/dL (4.5-12.0mcg/L), and cortisol 8.9mcg/dL (low in pregnancy) obtained at 0535. Intravenous (IV) corticosteroids followed by IV levothyroxine were initiated. Total T3 and T4 labs were collected to monitor treatment response as free T3/T4 pregnancy reference ranges were not available. The patient improved and underwent cesarean section on hospital day two. Post-operatively, she became increasingly lethargic, hypothermic (temperature 96.2F), bradycardic (heart rate 40), and hypoxemic (oxygenation level 87%), consistent with myxedema coma. Liothyronine was initiated, she recovered and was discharged home.
Discussion: Myxedema coma is a rare endocrine emergency, that left untreated, carries a high mortality. Prompt recognition and multidisciplinary efforts to provide treatment in this case saved not one, but two lives. Often precipitated by a stressor, decompensation of severe hypothyroidism can affect almost every organ system. Close laboratory interpretation is required as interpretation of normal reference ranges vary between laboratories and expected values change with pregnancy. Initial treatment is intravenous hydrocortisone followed by thyroid hormone administration. Hydrocortisone is recommended first due to possible co-existing adrenal insufficiency and because thyroid hormone administration may increase cortisol clearance and precipitate adrenal insufficiency. The optimal mode of thyroid hormone replacement is controversial, but IV administration is often preferred. Some recommend adding liothyronine if clinical response is poor.
