MON-445 A Fatal Case of Refractory Myxedema Coma with Multiorgan Failure

Abstract Disclosure: H. Angammana: None. M. Park: None. J. Pesantez: None. A. Sajan: None. Introduction: Myxedema coma is a rare endocrine emergency characterized by profound hypothyroidism with high mortality, often precipitated by infection, medication noncompliance or systemic illness. We present a case of refractory fatal myxedema coma complicated by acute hypoxic respiratory failure, septic shock and multiorgan failure. Case Presentation: A 79-year-old female with a history of hypothyroidism presented with progressively worsening lethargy for few days. She had been noncompliant with levothyroxine for several months. On admission, she was obtunded, hypothermic (90.5 °F), bradycardic (46 beats per minute), and hypotensive (88/50 mmHg). The physical exam revealed facial puffiness, periorbital edema, and generalized non-pitting edema. The laboratory findings were significant for Thyroid Stimulating Hormone (TSH) of 74 IU/mL [0.4-4.0] and free thyroxine (FT4) of 0.27 ng/dL [0.8-1.8]. She also had elevated white blood count (18.2 x10^9/L [4-11 x10^9]), elevated creatinine of 2.1 mg/dL [0.6-1.1], and hyponatremia (127 mmol/L [135-145]). She developed pneumonia with worsening respiratory distress and was intubated for airway protection. Shortly after, she had a lower gastrointestinal bleed requiring multiple blood transfusions. The patient was promptly started on intravenous levothyroxine, liothyronine, hydrocortisone, antibiotics and supportive care. Following initial stabilization, her TSH had improved to 4.76 IU/mL and mental status improved. She was subsequently downgraded to the general medical floor. However, she soon deteriorated in a few days with acute kidney injury requiring renal replacement therapy, newly diagnosed heart failure with a reduced ejection fraction (20%), bilateral pleural effusions and decubitus ulcers with osteomyelitis. She reverted to being lethargic and had a cardiac arrest secondary to aspiration. Given her poor prognosis, care was transitioned to comfort measures, and she passed away under hospice care. Her last drawn TSH was 13.83 IU/ml while on intravenous levothyroxine and liothyronine. Discussion: Myxedema coma continues to have a high mortality rate of about 50%. Predictors of poor prognosis include advanced age, persistent hypothermia, hypotension, bradycardia, sepsis, mechanical ventilation. The prognosis of myxedema coma remains difficult to determine due to its rarity. While early diagnosis and aggressive management have improved survival rates, complications such as sepsis, respiratory failure, and multiorgan dysfunction still result in poor outcomes like in our patient. Further research is needed to refine prognostic models and explore novel therapeutic strategies to improve survival in these patients. Presentation: Monday, July 14, 2025