Adrenal Insufficiency in the Intensive Care Setting

Abstract

Adrenal insufficiency is a challenging problem for critical care physicians. Failure to recognize its presence and to institute appropriate therapy when the patient is ill enough to require intensive care can lead to a life-threatening situation. This review covers the circumstances under which adrenal insufficiency should be suspected, the steps necessary to document adrenal dysfunction, and the appropriate therapy. Normal Response of the Adrenal Glands to Stress Measurement of Cortisol Concentrations in Stress.Definition of the normal adrenal response to a variety of stresses has been established by a number of studies. Shortly after it became possible to measure glucocorticoid levels, initial determinations showed plasma cortisol concentrations to be 4 to 5 times above normal in moribund patients [ 1 These patients, moreover, did not experience the usual increase in cortisol levels after administration of adrenocorticotrophic hormone (ACTH). Similar elevated plasma concentrations of cortisol were reported in patients suffering from septic shock [2] and in dogs given endotoxin [3]. In the study by Melby and colleagues [3], the importance of intact hypophyseal function for the stress-associated increases of cortisol was established, because no increase occurred if dogs had been hypophysectomized. Other acute stresses, such as those caused by severe trauma [4], sepsis without shock [5], and surgical procedures [6,7], are associated with 2to 3-fold increases in plasma cortisol concentrations. The stress from surgical procedures is so powerful that the increase in cortisol cannot be prevented by the concomitant administration of exogenous glucocorticoid steroid [7], which under ordinary circumstances would suppress endogenous glucocorticoid production. Similar cortisol increases usually occur in infections with fever [8][9][10][11] and may also be accompanied by a loss in normal circadian rhythm [9] that is characteristic of corticosteroids. Occasional instances of normal plasma cor-

Corticosteroid Therapy in Severe Illness

“…Se-rum cortisol concentrations that are regarded as normal in normal subjects may be inappropriately low in patients who are severely ill, suggesting the existence of relative adrenal insufficiency. For example, a cortisol concentration of less than 10 m g per deciliter (276 nmol per liter) in a random serum sample has been proposed as abnormal during acute illness 37 and, conversely, serum cortisol concentrations above 18 m g per deciliter (497 nmol per liter) after corticotropin stimulation as indicating adequate adrenal reserve.…”

Lesson of the Week: Adrenocortical failure in intensive care

“…The classic features of hyponatraemia and hyperkalaemia may not be present (as in this case) or may be attributed to inappropriate intravenous fluid replacement. A random cortisol concentration of <280 nmol/l has been suggested as diagnostic of acute adrenal insufficiency in acute illness 4. Clayton suggested that the best method to evaluate adrenal function is the stimulation test with low dose tetracosactrin 5.…”

“…If a patient's life is in danger dexamethasone should be given without waiting for the results of cortisol assays, as it provides the glucocorticoid effects (but not mineralocorticoid effects) of cortisol without interfering with further stimulation testing with tetracosactrin 4. After acute adrenocortical failure has been diagnosed hydrocortisone should replace the dexamethasone to provide both glucocorticoid and mineralocorticoid effects.…”

Adrenal Insufficiency In Critically Ill Patients

“…Adrenal insufficiency is estimated to occur at a rate of 0-30% in the critically ill population 13,14 and may be as high as 25-40% in patients with septic shock, 15,16 depending on the specific tests and threshold used to diagnose adrenal insufficiency, underlying disease, and severity of illness. Absolute adrenal insufficiency is rare among critically ill patients, with an incidence estimated to be ≤3 percent 25 .…”

“…17 Although absolute adrenal insufficiency is quite rare in critically ill patients, relative adrenal insufficiency is considerably more common. 18 In chronic critical illness, adrenal insufficiency may also result from catecholamine receptor desensitization or down-regulation and/or chronic secretion of cytokines and other substances that suppress the HPA axis. This latter mechanism is sometimes called adrenal exhaustion syndrome.…”