Free and total cortisol levels are useful prognostic markers in critically ill patients: a prospective observational study.

OBJECTIVE The role of cortisol in the prediction of mortality risk in critical illness is controversial in the literature. The aim of this study was to evaluate the prognostic value of cortisol concentrations in a mixed population of critically ill patients in medical emergencies. DESIGN In this prospective, observational study, measurement of total (TC) and free cortisol (FC) levels was made in the serum samples of 69 critically ill patients (39 males and 30 females, median age of 74 years) at admission (0 h) and 6, 24, 48, and 96 h after admission. METHODS Cortisol levels were determined using HPLC coupled high-resolution ESI-TOF mass spectrometry. The severity of disease was calculated by prognostic scores. Statistical analyses were performed using the SPSS 22.0 software. RESULTS The range of TC varied between 49.9 and 8797.8 nmol/l, FC between 0.4 and 759.9 nmol/l. The levels of FC at 0, 6, 24, and 48 h and TC at 0, 6 h were significantly elevated in non-survivors and correlated with the predicted mortality. The prognostic value of these cortisol levels was comparable with the routinely used mortality scores. In predictive models, FC at 6, 24, and 48 h proved to be an independent determinant of mortality. CONCLUSIONS The predictive values of FC in the first 2 days after admission and TC within 6 h are comparable with the complex, routinely used mortality scores in evaluating the prognosis of critically ill patients. The cortisol response probably reflects the severity of disease.