Endocrine Abstracts

Introduction: Both cortisol and vasopressin are stress hormones. Earlier, our group demonstrated that serum concentrations of free cortisol at admissions to the Intensive Care Unit (ICU) were independent predictors of survival in critically ill patients. Other investigators have demonstrated that serum copeptin, a surrogate marker of vasopressin may also be a predictive factor in this patient population. The aim of our present study was to compare the prognostic roles of serum levels of cortisol and copeptin.

Methods: In the 69 critically ill patients (39 male, 30 female, mean age 69±11 ys) in whom cortisol levels were determined earlier, serum concentrations of copeptin were measured in their stored samples which had been taken shortly after admission to ICU, using ELISA kits (Abbexa Ltd). The severity of the disease was calculated based on the SAPS II and APACHE II scoring systems. Statistical analyses were performed using SPSS 22.0 and MedCalc 13.3.3.0.

Results: Copeptin, total and free cortisol levels were typically highly elevated: baseline values (ranges) were as follows: 1409.7 pg/mL (98.1–6143.9), 1101.6 nmol/L (112.6–8797.8) and 106.2 nmol/L (0.4–759.9), respectively. Furthermore, these concentrations were significantly (i) higher in non-survivors than in surviving patients with medians (inter-quartiles) 1130.5 pg/mL (778.0–2663.1) vs 770.2 pg/mL (415.9–1672.3), 1141.3 nm/L (744.6–2154.2) vs 634.0 nm/L (394.9–987.4), and 178.7 nm/L (33.3–278.7) vs 15.1 nm/L (4.4–80.4), respectively and (ii) correlated with APACHE II (R=0.331; 0.455; and 0.559, respectively) and SAPS II (R=0.382; 0.542; and 0.584, respectively) scores. However, in respect to predicting mortality, compared to free cortisol, copeptin (i) showed lower area under the curve during receiver operating characteristic (0.679 vs 0.801), and (ii) was not an independent predictor in multiple binary logistic regression analyses.

Conclusion: In respect of critically ill patients’ prognosis, the predictive power of free cortisol is higher than of copeptin.