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- EU:
- USA: For Research Use Only. Not For Use In Diagnostic Procedures.
Cortisol is the most abundant circulating steroid and the major glucocorticoid secreted by the adrenal cortex. Cortisol is physiologically effective in blood pressure maintenance and anti-inflammatory activity. It is also involved in calcium absorption, gluconeogenesis as well as the secretion of gastric acid and pepsin. The levels of cortisol are increased under stress situations, physical exercise and external administration of ACTH.
Most circulating cortisol is bound to corticosteroid-binding globulin (transcortin) and albumin. The amount of unbound or free cortisol (which is considered the active fraction in blood), represents approximately 1–2% of the total amount in blood.
The measurement of salivary cortisol is considered to represent the free fraction, due to the absence of appreciable amounts of cortisol-binding proteins in saliva. The level of salivary cortisol shows a diurnal rhythm with the highest levels in the morning and the lowest levels at night. Studies consistently report high correlations between serum and salivary cortisol, indicating that salivary cortisol levels reliably estimate serum cortisol levels.
The measurement of salivary cortisol levels can be used as an indicator of adrenal function and the differential diagnosis of Addison’s and Cushing’s diseases.