Document Type

Article

Publication Title

Cureus

Abstract

Hypothyroidism affects a large subset of the population, with many undiagnosed. In iodine-sufficient regions, chronic autoimmune thyroiditis (Hashimoto’s) is the leading cause. Chronic, untreated hypothyroidism can result in multisystem complications, including cardiovascular disease, infertility, and respiratory failure. The most severe presentation, myxedema, is a medical emergency marked by altered mentation, ranging from lethargy to coma, hypothermia, and hypoventilation. Prompt recognition and treatment with thyroid hormone replacement are essential to improve outcomes. We present a case of hypercapnic respiratory failure secondary to myxedema coma. A 51-year-old female with morbid obesity (BMI 39.9 kg/m²) presented unresponsive, hypoxemic, and cyanotic, requiring emergent intubation. Labs revealed severe anemia (Hb 6.5 g/dL) and respiratory acidosis. The urinalysis was positive for infection, and the urine culture grew Escherichia (E.) coli. Imaging showed small pericardial and pleural effusions, and echocardiography revealed preserved ejection fraction (55%). Thyroid studies confirmed severe hypothyroidism with thyroid-stimulating hormone (TSH) 38.2 mIU/L and free thyroxine (T₄) < 0.07 ng/dL, consistent with myxedema coma. She was managed with IV levothyroxine, IV hydrocortisone, antibiotics, ventilatory support, diuresis, and electrolyte repletion. Following thyroid hormone therapy, her respiratory status and mentation improved, allowing extubation and discharge after 14 days on 2 L home oxygen.

Myxedema coma-induced hypercapnic respiratory failure occurs through reduced central respiratory drive, respiratory muscle weakness, and impaired gas exchange from pleural effusions or pneumonia. Studies have shown diminished maximal inspiratory and expiratory pressures in hypothyroid patients, reversible with hormone replacement. Pericardial effusion, observed in up to one-third of severe hypothyroid cases, results from increased capillary permeability and typically resolves with levothyroxine therapy without invasive intervention. Hypercapnic respiratory failure secondary to myxedema coma is rare but life-threatening. Early diagnosis and thyroid hormone replacement are essential to prevent morbidity and mortality. Clinical vigilance is required for patients with unexplained respiratory failure, particularly women with nonspecific hypothyroid symptoms. Ensuring medication adherence, thyroid function monitoring, and adequate respiratory support is vital for preventing recurrence and improving outcomes.

DOI

10.7759/cureus.109809

Publication Date

5-28-2026

Keywords

acute hypercapnic respiratory failure, critcal care, hypothyroid myxedema coma, respiratory support, thyroid pathology

ISSN

2168-8184

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