Spectrum of serum cortisol response to ACTH in ICU patients. Correlation with degree of illness and mortality.

Recent reports suggest adrenal insufficiency in critically ill patients is common. We found only one case of de novo adrenal insufficiency using admission ACTH injection in 70 selected intensive care unit (ICU) patients. Random serum cortisol levels correlated positively with illness severity in ICU patients using proven methods for assessing illness severity. Those with the highest random serum cortisol levels (greater than 60 micrograms/dl) had the greatest mortality, while those with lower random cortisol levels which stimulated to more than 18 micrograms/dl after ACTH injection had improved outcomes. Based on our results, routine screening for adrenal insufficiency in ICU patients is not warranted. If it is suspected, the cosyntropin test should be performed since low random cortisol levels (even to 5 micrograms/dl) are not diagnostic of adrenal insufficiency.