Synopsis
Recognise decompensated severe hypothyroidism before coma is established, deliver endocrine-critical-care treatment in the correct sequence, and correct precipitating and metabolic threats safely.
- The syndrome is severe physiological decompensation from hypothyroidism and does not require literal coma; altered cognition may range from slowing and delirium to unresponsiveness.
- Think of the cluster: hypothermia, bradycardia, hypotension, hypoventilation or hypercapnia, hyponatraemia, hypoglycaemia, oedematous appearance and reduced consciousness.
- Infection, cold exposure, myocardial infarction, stroke, sedatives or opioids, surgery and interruption of levothyroxine are important precipitants.
Key red flags
Lethargy, slowed responses, confusion, psychosis, seizures, stupor or coma may occur. A fall in consciousness alongside hypothermia or bradycardia is particularly concerning and mandates airway assessment.
Investigation priorities
Identify immediate ventilatory, circulatory and thermoregulatory failure.
Management branches
Severe hypothyroid decompensation is clinically suspected.
- Call critical care, endocrinology and senior acute support; perform ABCDE with continuous ECG, core temperature, glucose and urine-output monitoring.
- Secure oxygenation and ventilation, obtain blood gas and prepare intubation when consciousness or carbon-dioxide clearance is inadequate.
Key medicines
Hydrocortisone emergency coverCommon UK emergency practice begins with 100 mg intravenously or intramuscularly, followed by the current adrenal-crisis schedule; verify ongoing dose and route with the BNF and local protocol.
Levothyroxine in myxoedema comaAfter glucocorticoid protection, give an adult intravenous loading dose of 200–500 micrograms, never exceeding 500 micrograms, then parenteral levothyroxine 1.2 micrograms/kg daily, usually 75–90 micrograms, with a lower-end or modified specialist plan for major cardiac risk.