The integrity of the hypothalamic-pituitary-adrenal axis is a major determinant of the host response to stress. Relative adrenal insufficiency has been implicated in poor outcome from systemic inflammatory states; however, whether low endogenous glucocorticoid levels are adaptive or pathologic remains controversial. The purpose of this study was to prospectively evaluate the cortisol response and determine the incidence of occult adrenal insufficiency after severe trauma.

Over an 18-month period, 22 severely injured patients admitted to the surgical intensive care unit of our level 1 trauma center were prospectively identified and followed. Demographic and outcome data were tabulated. In addition, random serum cortisol levels were obtained on days 0, 5, and 10 after injury. Relative adrenal insufficiency was defined as a random serum cortisol level less than 18 μg/dL.

Mean baseline cortisol levels were elevated (35 ± 3 μg/dL) and significantly declined over the next 10 days (day 5: 24 ± 2 μg/dL; and day 10: 22 ± 2 μg/dL; P <0.01). Thirteen of 22 (60%) patients had random serum cortisol levels less than 18 μg/dL. Only 1 of the 2 patients who died had a serum cortisol level less than 18 μg/dL. The mean cortisol levels at baseline were higher in the 2 patients who died compared with those who survived but this was not statistically significant (43.4 ± 8.8 μg/dL versus 35.0 ± 3.6 μg/dL, P = 0.5).

Serum cortisol levels increased immediately and gradually returned towards normal after severe trauma. Occult adrenal insufficiency was common (60%) in this small group of severely injured patients. This did not, however, affect mortality in these patients. Further study is needed to delineate the role of occult adrenal insufficiency after severe injury.