What is the Origin of Cortisol Secretion Profile?

This term is rooted in the discovery of the HPA axis and the subsequent realization that cortisol release is not constant but follows a robust, endogenously driven circadian rhythm. The use of the profile to assess health became practical with the development of non-invasive sampling methods, such as serial salivary or urine testing, which capture the rhythmicity across the entire day.

What is the Mechanism of Cortisol Secretion Profile?

Cortisol secretion is controlled by the suprachiasmatic nucleus (SCN), the brain's master clock, which signals the hypothalamus to release corticotropin-releasing hormone (CRH) in a rhythmic manner. CRH stimulates the pituitary to release adrenocorticotropic hormone (ACTH), which then travels to the adrenal glands to trigger cortisol synthesis and release. The resulting cortisol then exerts a negative feedback effect on both the hypothalamus and pituitary, completing the cycle and maintaining the precise 24-hour profile.

Cortisol Secretion Profile ∞ Area

Cortisol Secretion Profile

Meaning

The cortisol secretion profile is the characteristic 24-hour pattern of release of the glucocorticoid hormone cortisol from the adrenal cortex, which is a key diagnostic and monitoring tool in endocrinology. In healthy individuals, this profile exhibits a distinct diurnal variation, peaking sharply within the first hour of waking, known as the Cortisol Awakening Response (CAR), and gradually declining to its lowest point around midnight. Deviations from this predictable rhythm, rather than just single point-in-time measurements, indicate dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis.