Determination of Cortisol Levels in a Small Volume of Saliva of COVID-19-Recovering Patients During Treatment with Psychotropic Drugs.

Background/Objectives: Cortisol levels are increased in stressful situations but can also result from a history of COVID-19 infection. Long-term exposure to high cortisol levels has a destructive effect on the CNS (Central Nervous System) and can lead to depression, among other things. The most commonly used psychotropic drugs reduce cortisol concentrations. Methods: The aim of our study was to develop an analytical method to determine the level of the hormone in a small volume of saliva (200 µL) in COVID-19 patients using CNS-active drugs. Solid-phase extraction was used to isolate the analyte, and the determination was performed by liquid chromatography with a diode array detector (LC with DAD). Results: The developed method was validated. Its linearity was determined to be in the range of 4-500 ng/mL (R² > 0.9986) and the intra- and inter-day precision expressed as coefficient of variation (CV%) did not exceed 12%. The method was then applied to determine cortisol levels in the saliva of post-COVID-19-recovered patients and healthy volunteers. The determined cortisol levels were 12.24 ± 7.33 ng/mL in the recovered patients and 4.11 ± 1.46 ng/mL in the healthy subjects, respectively. A comparison of the results showed that cortisol levels in the recovered patients and healthy volunteers were significantly different statistically. Conclusions: The developed method allowed for the determination of cortisol in a small volume of saliva. Comparison of cortisol concentration in healthy individuals and COVID-19 recoveries indicates that the hormone level in both groups significantly differed statistically, and the psychotropic drugs used did not reduce cortisol concentration in COVID-19 patients. The results obtained indicate that the psychotropic drugs used did not reduce cortisol concentrations in COVID-19 patients.