Cortisol measured in saliva is an alternative way of measuring the hormone. Its monitoring is used to distinguish between primary and secondary adrenal insufficiency and to diagnose Cushing's syndrome differentially.
In addition, the cortisol measurement in the saliva is used to study the disorders of the daily (circadian) secretion rhythm and to diagnose conditions such as adrenal stress or exhaustion.
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Cortisol or hydrocortisone is the primary glucocorticoid hormone produced in the adrenal cortex. Cortisol is actively involved in regulating calcium absorption and maintaining blood pressure; it has anti-inflammatory actions, regulates gluconeogenesis, gastric acid, and pepsin secretion, and regulates immune function. Cortisol production shows a daily (circadian) rhythm. Its levels peak early in the morning and fall to their lowest at night. Cortisol levels rise regardless of circadian rhythm in response to stress. Elevated cortisol production is associated with Cushing's syndrome and adrenal tumors, while decreased cortisol production is associated with adrenal insufficiency (e.g., Addison's disease) and adrenocorticotropic hormone (ACTH) deficiency.
Only 1 to 15% of cortisol in the blood is unbound or biologically active. The remaining cortisol binds to serum proteins. Free serum cortisol enters saliva through specific intracellular mechanisms, while most cortisol in saliva remains unbound to proteins.
Salivary cortisol levels are not affected by salivary flow rate or salivary enzymes. Many studies report high correlations between serum and salivary cortisol measurements, indicating that salivary cortisol levels reliably assess cortisol levels in the body.
Measurements of hormones in saliva are an excellent choice because the sample collection is non-invasive and easy, without the possible complications and inconvenience of blood sampling, while ensuring the sensitivity and accuracy of the measurements.
