myxoedema coma

a life-threatening condition due to severe hypothyroidism, which is often precipitated by an acute event, such as surgery, prolonged exposure to cold, infection, trauma, other severe illness, or sedative drugs. It manifests as hypothermia, slowing of the heart rate with a reduction in blood pressure and sometimes heart failure, pleural and peritoneal effusions, urinary retention, and a gradually reduced conscious state resulting in coma. Blood tests show hypothyroidism, hyponatraemia, hypercholesterolaemia, retention of carbon dioxide, and anaemia. Treatment is with intravenous thyroxine at a high dosage until the patient wakes up, when tablets can be administered. Support on a ventilator and using intravenous fluids may be needed. Active slow rewarming should be undertaken.