What is the Origin of Salivary Cortisol Curve?

This testing methodology emerged from the clinical need for a non-invasive, free-circulating measure of cortisol that accurately reflects biologically active hormone levels, unlike total serum cortisol. The curve format is essential for visualizing the temporal pattern of secretion, which is a far more sensitive indicator of HPA axis health than a single static measurement.

What is the Mechanism of Salivary Cortisol Curve?

Saliva collects the free, unbound fraction of cortisol that has diffused from the blood, which represents the biologically active portion of the hormone capable of binding to intracellular receptors and eliciting a physiological response. Plotting the curve allows the clinician to identify specific patterns of dysregulation, such as a flattened curve (indicative of HPA axis exhaustion) or an exaggerated evening rise, which are classic signs of chronic stress or HPA axis maladaptation.

Salivary Cortisol Curve ∞ Area

Salivary Cortisol Curve

Meaning

The Salivary Cortisol Curve is a diagnostic representation of the diurnal rhythm of the active stress hormone cortisol, measured by collecting multiple saliva samples throughout a single day, typically four or more time points. This non-invasive test plots the physiological pattern of cortisol release from the adrenal glands, which should exhibit a characteristic peak shortly after waking, known as the Cortisol Awakening Response (CAR), and a gradual decline throughout the day. It is a key tool for accurately assessing the functional integrity of the Hypothalamic-Pituitary-Adrenal (HPA) axis.