[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Myxoedema coma [Conditions](https://durgical.com/en/conditions/) · [Endocrinology](https://durgical.com/en/conditions/) # Myxoedema coma Myxoedema coma is the most severe, life-threatening form of an underactive thyroid, with low temperature, slowed breathing and confusion. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) - [Pituitary gland](https://durgical.com/en/anatomy/pituitary-gland/) - [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/) ## In the clinical exam - [Hyperthyroidism and hypothyroidism: the signs](https://durgical.com/en/clinical-exam/hyperthyroidism-and-hypothyroidism-the-signs/) ## Why it happens - [Actions of thyroid hormones](https://durgical.com/en/physiology/actions-of-thyroid-hormones/) - [The thyroid axis: reading TSH and free T4](https://durgical.com/en/physiology/the-thyroid-axis-reading-tsh-and-free-t4/) - [Body temperature regulation](https://durgical.com/en/physiology/body-temperature-regulation/) - [Hypothermia and cold injury](https://durgical.com/en/physiology/hypothermia-and-cold-injury/) - [ADH, thirst and water balance](https://durgical.com/en/physiology/adh-thirst-and-water-balance/) ## What it is Decompensated severe hypothyroidism with altered mental status, hypothermia and failure of several organ systems. Despite the name, many patients are not in coma; it is a medical emergency. ## Who gets it Rare. It mostly affects older women with long-standing untreated or undertreated hypothyroidism, usually in the cold months and after a precipitating event. Mortality is high. ## Causes - Long-standing primary hypothyroidism (autoimmune Hashimoto thyroiditis, after thyroidectomy or radioiodine), rarely central hypothyroidism - Trigger: infection, especially pneumonia or urinary infection - Cold exposure - Sedatives, opioids, anaesthesia or other drugs that depress the brain - Stroke, myocardial infarction, heart failure, gastrointestinal bleeding or trauma - Stopping thyroid hormone replacement ## Risk factors - Older age and female sex - Untreated or poorly adherent hypothyroidism - Winter or cold environment - Admission to hospital with sedative use ## Pathophysiology Severe lack of thyroid hormone slows metabolism and thermogenesis, depresses the respiratory drive and heart, and reduces free-water clearance. A stressor tips this fragile balance: hypothermia, hypoventilation with carbon dioxide retention, bradycardia, hyponatraemia and hypoglycaemia follow and worsen the mental state. ## Symptoms and signs - Confusion, lethargy, stupor or coma - Hypothermia, often without shivering - Bradycardia, hypotension and slow, shallow breathing - Dry [skin](https://durgical.com/en/anatomy/skin/), non-pitting swelling of face and hands, thin hair, macroglossia - Delayed relaxation of tendon reflexes; a thyroidectomy scar may give a clue ## Red flags - Hypothermia with depressed consciousness - Hypoventilation with rising carbon dioxide - Hypotension unresponsive to fluids - Seizures, often from hyponatraemia or hypoglycaemia ## Diagnosis **Clinical** Suspected in a hypothermic, drowsy patient with signs or history of hypothyroidism. A diagnostic score exists, but treatment starts on clinical suspicion once blood is drawn. **Tests** Very high TSH with low free T4 in primary hypothyroidism (TSH may be low or normal in central forms). Arterial blood gas with hypercapnia, hyponatraemia, hypoglycaemia, raised creatine kinase; cortisol drawn before steroids; cultures to look for infection. **Imaging** [Chest](https://durgical.com/en/anatomy/region/chest/) X-ray for pneumonia or pericardial effusion; echocardiography for effusion; head CT when another cause of coma must be excluded. ## Differential diagnosis - Sepsis - Hypothermia from environmental exposure - Adrenal crisis - Stroke or other structural brain lesion - Sedative or opioid overdose ## Goal of treatment Replace thyroid hormone, cover possible adrenal insufficiency, support breathing, circulation and temperature, and treat the trigger. ## Treatment **Medical** Intravenous thyroid hormone (levothyroxine, sometimes with liothyronine), adjusted carefully in older patients and those with heart disease. **Medical** Intravenous glucocorticoids until coexisting adrenal insufficiency is ruled out. **Acute** Intensive care support: airway protection and mechanical ventilation if needed, passive rewarming, cautious fluids, correction of hyponatraemia and hypoglycaemia, empirical antibiotics when infection is suspected. **Follow-up** Core temperature, cardiac rhythm, blood gases, sodium and glucose; nursing focus on airway, slow rewarming, pressure-area care and avoiding sedatives. ## Complications - Respiratory failure - Shock and arrhythmias, especially when hormone is replaced too fast - Severe hyponatraemia with seizures - Pericardial effusion and, rarely, tamponade - Death ## Prognosis Mortality is high, especially in older patients with severe hypothermia, low consciousness or heart disease. Survivors need lifelong thyroid hormone replacement and follow-up. ## Prevention - Diagnosis and adequate replacement of hypothyroidism - Caution with sedatives and opioids in hypothyroid patients ## Test yourself Think of the answer, then tap the question to see it. ## Why are glucocorticoids given with thyroid hormone in myxoedema coma? Coexisting adrenal insufficiency is possible, and thyroid hormone raises cortisol clearance and could precipitate an adrenal crisis. ## How is hypothermia managed in myxoedema coma? With passive rewarming (blankets, warm room); active external rewarming can cause vasodilation and collapse. ## Which electrolyte disorder is typical of myxoedema coma? Hyponatraemia, from reduced free-water clearance. ## What is the most common trigger of myxoedema coma? Infection, especially pneumonia, often with cold exposure or sedative drugs. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/myxoedema-coma/) ## Related conditions - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) - [Adrenal insufficiency](https://durgical.com/en/conditions/adrenal-insufficiency/) - [Adrenal crisis](https://durgical.com/en/conditions/adrenal-crisis/) - [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/) - [Heart failure](https://durgical.com/en/conditions/heart-failure/) - [Thyroid storm](https://durgical.com/en/conditions/thyroid-storm/) - [Hypoglycaemia (including insulin-induced)](https://durgical.com/en/conditions/hypoglycaemia/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Hypothyroidism](https://medlineplus.gov/ency/article/000353.htm) (MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), 2024); Myxedema Coma (StatPearls (NCBI Bookshelf), 2023). 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