What is the Origin of Cortisol Diurnal Slope?

This term originates from chronobiology and endocrinology, specifically relating to the rhythmic, time-dependent secretion patterns inherent to many hormones, including glucocorticoids. Diurnal refers to the daily cycle, while slope describes the calculated rate of change over that time course. It is a vital metric in assessing adrenal health beyond a single snapshot measurement.

What is the Mechanism of Cortisol Diurnal Slope?

The mechanism relies on the pulsatile release of ACTH from the pituitary, which drives the adrenal cortex to secrete cortisol according to a circadian rhythm dictated by the suprachiasmatic nucleus. A steep, negative slope indicates successful negative feedback loops and timely clearance of the hormone post-stimulation. Deviation suggests impairment in the hypothalamic-pituitary-adrenal axis feedback sensitivity or rhythmicity.

Cortisol Diurnal Slope

Meaning

The Cortisol Diurnal Slope quantifies the expected rate of decline in circulating cortisol levels from the morning peak (often around 8 AM) to the evening trough, typically measured over a 24-hour period or a defined subset. A healthy slope reflects robust HPA axis function, signaling appropriate timing for metabolic and stress responses. Flattening or inversion of this slope is a critical clinical indicator of adrenal dysregulation or chronic stress impact.