SAT-392 Myxedema Coma as a Rare Cause of Shock

Abstract Disclosure: B. Celik: None. D. Shelden: None. Introduction: Myxedema coma (MC) is a rare condition that is caused by severe hypothyroidism. It has an estimated incidence of 2.6 cases per million per year. MC can cause hypothermia, bradycardia, hypotension, and even shock. Here we present a patient with shock caused by MC.Clinical Case: An 86-year-old female with hypothyroidism presented with shortness of breath and lethargy. On the initial examination, heart rate was 45 beats per minute, blood pressure was 94/57 mmHg, and temperature was 93.2°F. The patient was lethargic, and her extremities were cold. Laboratory workup showed TSH of 34.6 mcIU/mL (n: 0.4 - 4.5 mcIU/mL), free T4 of 0.7 ng/dL (n: 0.7 – 1.5 ng/dL), undetectable free T3 (n: 1.7 – 3.7 pg/mL), and lactic acid of 3.8 mmol/L (n < 2 mmol/L). ECG showed sinus bradycardia, and chest X-ray showed bilateral pleural effusions. Myxedema coma score was 75. The patient was put on IV levothyroxine and solumedrol. Epinephrine, norepinephrine, and vasopressin infusions were started due to resistant hypotension. Hypotension persisted despite multiple high-dose vasopressors. The Fick formula showed decreased cardiac index and output. Dobutamine infusion was started, which resulted in decreased vasopressor requirements. Thoracentesis of pleural effusions was done, and fluid studies were consistent with a transudate. A transthoracic echocardiogram (echo) was done and showed preserved ejection fraction (EF). TSH improved to 8.14 mcIU/mL, and free T4 improved to 0.9 ng/dL. The patient’s mental status improved, hypotension resolved, and vasopressors were weaned off.Clinical lessons: MC is a rare diagnosis due to widespread use of thyroid function tests and early diagnosis of hypothyroidism, but it still has a very high mortality rate, up to 30%. Although the treatment of MC is well established, insufficient data exist regarding the management of cardiovascular complications associated with MC. Low intracellular T3 leads to depressed cardiac functions with decreased inotropism and chronotropism. Our patient presented with persistent bradycardia and hypotension requiring atropine use and multiple high-dose vasopressor infusions. Despite the Fick formula showing low cardiac index and output, echo showed preserved EF. This is most likely caused by dobutamine infusion, which started prior to the echo. Hormone replacement therapy with intravenous levothyroxine is the mainstay of treatment in MC. Studies show that with appropriate thyroid hormone treatment, cardiovascular function can be restored, but as observed in our case, this recovery can take time, and patients might need inotropic support in the meantime. Cardiac complications significantly increase the mortality rate of MC, up to 60%. Prompt recognition and management of cardiovascular dysfunction are crucial for improving outcomes. Physicians should not hesitate to obtain an early echo and use inotropic support if needed. Presentation: Saturday, July 12, 2025