What is the Origin of HPA Axis Reactivity Testing?

This methodology is a refinement of traditional endocrinological stress tests, such as the ACTH stimulation test, adapted for the functional medicine context to detect subtle, non-pathological dysregulations. The concept of "reactivity" emphasizes the dynamic, time-dependent nature of the stress response, which is a more sensitive indicator of functional health than basal hormone levels alone. It is foundational to understanding stress-related hormonal patterns.

What is the Mechanism of HPA Axis Reactivity Testing?

The test typically measures cortisol and sometimes DHEA at four or more time points, providing a functional curve that reveals patterns of hyper- or hypocortisolism, or blunted responses. The mechanism relies on the physiological feedback loop where the hypothalamus releases CRH, stimulating the pituitary to release ACTH, which then prompts the adrenal glands to secrete cortisol. Deviations from the normal curve indicate dysregulation at one or more points in this axis, often due to chronic stress-induced altered receptor sensitivity.

HPA Axis Reactivity Testing ∞ Area

HPA Axis Reactivity Testing

Meaning

HPA Axis Reactivity Testing is a specialized diagnostic procedure designed to evaluate the dynamic functional reserve and responsiveness of the Hypothalamic-Pituitary-Adrenal axis, the central stress response system. Unlike a single-point cortisol measurement, this testing involves collecting multiple samples, often saliva or urine, throughout the day and in response to a controlled stimulus to map the diurnal rhythm and stress-induced output. This detailed analysis provides critical insight into the individual’s adaptive capacity to stress.