Many cases occur in the elderly during the winter, with the patient unable to respond to impending hypothermia.
Mechanisms:
(1) physiologic or metabolic stress
(2) altered release, protein binding or metabolism of thyroid hormones
Conditions associated with physiologic and/or metabolic stress:
(1) extensive burns
(2) surgery or trauma
(3) hypothermia
(4) hypoglycemia
(5) acute hemorrhage
(6) hypercarbia (hypercapnia)
(7) stroke
(8) acute infection (pneumonia, urinary tract infection, sepsis, etc.)
(9) acute myocardial infarction
Medications that can precipitate myxedema coma:
(1) amiodarone
(2) general anesthesia (often mixed with major surgery or trauma)
(3) barbiturates
(4) beta blockers
(5) lithium
(6) diuretics
(7) narcotic analgesics
(8) phenothiazines
(9) phenytoin
(10) rifampin
(11) benzodiazepines or other tranquilizers
Failure to maintain thyroid replacement therapy while hospitalized can result in myxedema coma, especially if there is significant metabolic stress.
