Objective: Serum cortisol levels rise in response to the stress of critical illness but the optimal range of serum cortisol in such settings is not clearly defined. The objectives of this study were to determine the range of serum cortisol levels in a group of medical intensive care unit patients with severe sepsis/septic shock using uniform criteria, and to correlate serum cortisol levels to mortality.
Design and patients: In a prospective observational fashion, 100 medical intensive care unit patients at Northwestern Memorial Hospital in Chicago were enrolled within 48 h of developing severe sepsis/septic shock as defined by the American College of Chest Physicians/Society of Critical Care Medicine.
Measurements: A serum cortisol level was measured during the morning hours in the first 48 h of developing severe sepsis/septic shock. The severity of critical illness was measured by the Acute Physiology and Chronic Health Evaluation II (APACHE II) score.
Results: The average patient age was 63 +/- 17 years, 54 patients were men. The average APACHE II score for all patients was 23 +/- 7. In-hospital and 90-day mortality were 51% and 60%, respectively. Four patient groups were defined a priori based on morning serum cortisol levels and their in-hospital mortalities were as follows: group 1 (cortisol < or = 345 nmol/l), n = 11, mortality 54%; group 2 (cortisol 345-552 nmol/l), n = 19, mortality 53%; group 3 (cortisol 552-1242 nmol/l), n = 54, mortality 41%; and group 4 (cortisol > or = 1242 nmol/l), n = 16, mortality 81% (P < 0.01).
Conclusions: Cortisol levels were elevated in most patients with septic shock. Cortisol levels less than 552 nmol/l occurred in 30% of patients with septic shock but the mortality in these patients was not significantly increased. Serum cortisol levels > or = 1242 nmol/l were associated with significantly higher mortality.