Cardiac arrest is one of the leading causes of death and represents maximal stress in humans.After restoration of spontaneous circulation,post-cardiac arrest syndrome is the predominant disorder in survivors.Besides the post-arrest brain injury,the post-resuscitation myocardial stunning,and the systemic ischemia/reperfusion response,this syndrome is characterized by adrenal insufficiency,a disorder that often remains undiagnosed.The pathophysiology of adrenal insufficiency has not been elucidated.We performed a comprehensive search of three medical databases in order to describe the major pathophysiological disturbances which are responsible for the occurrence of the disorder.Based on the available evidence,this article will help physicians to better evaluate and understand the hidden yet deadly post-cardiac arrest adrenal insufficiency.