Speakers - DEWC2025

Abstract

Background:
Myxedema coma is a rare but life-threatening manifestation of severe hypothyroidism, characterized by altered mental status, hypothermia, and multi-organ dysfunction. It is often triggered by infections, metabolic disturbances, or trauma. Individuals with Down syndrome (DS) are at an increased risk of developing hypothyroidism due to congenital thyroid abnormalities and autoimmune thyroid disease, making them more susceptible to myxedema coma. Additionally, DS is associated with increased risks of cardiac disease, immune dysfunction, and respiratory complications, further complicating the clinical picture. Here, we present a case of a 54-year-old female with DS who developed myxedema coma following trauma and poor oral intake.

Case Presentation:
A 54-year-old female with DS, previously independent in activities of daily living, presented with progressive generalized weakness, decreased verbal output, increased sleeping time, and a non-productive cough over three days. One month prior, she sustained a fall resulting in hip pain but was not evaluated. Her condition progressively worsened, leading to an emergency room consultation.

On examination, she was drowsy (Glasgow Coma Scale 12) but not in distress. Notable findings included puffy eyelids, dry skin, pretibial edema, bradycardia (heart rate of 58 bpm), and cold extremities. Laboratory investigations revealed profound hypothyroidism (TSH: 6.69 mIU/L, FT3: <0.391 pg/mL, FT4: <0.039 ng/dL), severe hyponatremia (Na+: 103.06 mmol/L), and laboratory findings suggestive of hypovolemic hypoosmolar hyponatremia. Chest imaging demonstrated pulmonary edema, possible pneumonia, and probable cardiomegaly.

She was diagnosed with myxedema coma and promptly managed with high-dose intravenous levothyroxine (200 mcg loading dose followed by 100 mcg every 8 hours), stress-dose hydrocortisone to prevent adrenal insufficiency, cautious sodium correction, and broad-spectrum antibiotics for suspected pneumonia. Supportive measures, including oxygen therapy via high-flow nasal cannula, were initiated in light of her partially compensated respiratory acidosis.

Despite thyroid hormone replacement and initial sodium correction, persistent hyponatremia prompted nephrology evaluation. Further workup revealed an underlying syndrome of inappropriate antidiuretic hormone secretion (SIADH), likely secondary to hypothyroidism, head trauma, and pneumonia. Tolvaptan and fluid restriction were initiated, leading to a gradual normalization of sodium levels. The patient's mental status steadily improved, and by hospital day 11, she was fully conscious (GCS 15) and hemodynamically stable. She was discharged on maintenance levothyroxine and advised for continued monitoring of thyroid function and electrolyte balance.

Conclusion:
This case underscores the complex interplay between hypothyroidism, trauma, and SIADH, particularly in individuals with DS. The presence of persistent hyponatremia despite thyroid hormone replacement necessitated a broader diagnostic approach, revealing SIADH as a contributing factor. Early recognition and aggressive management of myxedema coma are critical to improving outcomes. Furthermore, this case highlights the importance of multidisciplinary collaboration in managing endocrine, metabolic, and systemic complications in patients with DS. Given their predisposition to thyroid dysfunction and its severe manifestations, routine thyroid function screening and early intervention should be emphasized in this population to prevent life-threatening complications like myxedema coma.