Elevated corticosteroid level to meet physiologic needs during acute illness is a protective response for stress. This homeostasis is maintained by the hypothalamic-pituitary-adrenal (HPA) axis. However, inadequate response as corticosteroid insufficiency in critically ill patients is reported with increasing frequency, especially in severe sepsis and septic shock. Thus, corticosteroids could be beneficial for septic shock or severe acute illness.

Once considered as normal adrenal function, adrenal insufficiency may developed later with chronic critical illness as adrenal exhaustion syndrome. It is easily overlooked and is possible due to the chronic secretion of systemic cytokines or other HPA axis-suppressive substances. There is still no consensus how often adrenal function testing should be repeated, although a re-evaluation should be considered if clinical symptoms and signs suggest adrenal insufficiency or deteriorating clinical condition.