Spectral effect: each population must have its own normal midnight salivary cortisol reference values determined

Area of Science:

• Endocrinology
• Clinical Chemistry

Background:

• Midnight salivary cortisol (MSC) is a sensitive, non-invasive method for screening Cushing's syndrome, reflecting free plasma cortisol levels.
• Accurate diagnostic interpretation requires population-specific reference values due to potential influences of individual factors.

Purpose of the Study:

• To establish normal reference values for midnight salivary cortisol in a Turkish population.
• To investigate the influence of various individual factors on MSC levels.

Main Methods:

• 100 Turkish participants underwent physical examination and saliva collection at midnight.
• Salivary cortisol was measured using a luminescence immunoassay kit.
• Statistical analysis was performed to identify differences and correlations.

Main Results:

• The mean midnight salivary cortisol level in the healthy Turkish population was 0.21 ±0.03 µg/dl.
• Body mass index, age, sex, smoking, exercise, education, and alcohol consumption did not significantly affect MSC levels.

Conclusions:

• Normal salivary cortisol reference ranges are essential for accurate evaluation of pituitary-adrenal axis disorders.
• The findings underscore the need for population-specific reference values in clinical practice.