Myxedema coma is a rare condition requiring emergency care that can occur in a person who has untreated, severe hypothyroidism. It usually occurs in older adults who have other illnesses, such as a serious infection or heart attack, in addition to their hypothyroidism.

The following life-threatening symptoms may occur:

• Mental deterioration such as apathy, confusion, and psychosis
• Extremely low body temperature (hypothermia)
• Extremely slow heartbeat (fewer than 60 beats per minute)
• Heart failure
• Respiratory failure

Death can occur if myxedema coma is not treated. Emergency treatment may include thyroid replacement given in a vein (intravenously) and steroid therapy.