Comparison of Total, Salivary and Calculated Free Cortisol Levels in Patients With Severe Sepsis

More than 90% of circulating cortisol is predominantly bound to cortisol binding globulin (CBG), but also albumin. Thus, in the presence of both hypoalbuminemia and decreased CBG levels, the ratio of bound to free cortisol levels can be altered. In this situation, measurement of FC becomes more important. Direct FC measurement is time consuming and non-automated. Thus, some indirect methods to determine FC levels had been introduced. The Coolens' method may be practical to determine FC, it estimates FC levels from STC and CBG levels. In patients with CI, the synthesis of CBG and albumin is reduced leading to overestimation of adrenal insufficiency if we only use STC levels. Since some studies demonstrated that salivary cortisol (SaC) reflect free or unbound plasma cortisol levels, this method is used more often in clinical studies. STC and SaC levels at baseline and after ACTH stimulation had been used in some studies in patients with critical illness.

The aim of the present study was to compare STC, SaC and calculated free cortisol (cFC) levels at baseline and after the ACTH stimulation test in patients with SS and determine the suitability of SaC and cFC levels instead of STC for the diagnosis of adrenal insufficiency in patients with SS. And secondary aims of this study was to compare these parameters in patients with SS with healthy controls and check their effects on survival status of the patients.