Hair Cortisol Concentration ∞ Area

Hair Cortisol Concentration

Meaning

Hair Cortisol Concentration quantifies cortisol within hair strands, indicating cumulative systemic cortisol exposure over an extended period. This measurement provides insight into the body’s long-term physiological response to stressors, distinguishing it from transient daily fluctuations.

Context

Cortisol, a primary glucocorticoid from the adrenal cortex, plays a vital role in metabolism, immune function, and stress response within the endocrine system. Hair follicles are highly vascularized; circulating cortisol diffuses into the growing hair shaft, stably incorporating into its keratinized structure. This process allows hair to serve as a stable matrix for retrospective hormonal assessment.

Significance

The clinical importance of Hair Cortisol Concentration lies in its capacity for retrospective assessment of chronic HPA axis activity, often difficult to ascertain from single blood or saliva samples. Elevated or suppressed hair cortisol levels provide objective data for evaluating conditions associated with sustained stress, such as chronic fatigue, metabolic dysregulation, and endocrine disorders, informing intervention strategies.

Mechanism

Cortisol from systemic circulation enters the hair follicle via passive diffusion, incorporating directly into the developing hair shaft during its anagen phase. Within the hair matrix, cortisol is encapsulated by keratin proteins, remaining stable and resistant to degradation. As hair grows approximately one centimeter monthly, segments can be analyzed to reflect average cortisol levels over corresponding timeframes, providing a historical record.

Application

In clinical practice and research, Hair Cortisol Concentration analysis applies as a non-invasive method to assess prolonged physiological stress and adrenal function. It is valuable for investigating conditions where chronic cortisol exposure is suspected, such as in differential diagnosis of Cushing’s syndrome or chronic psychological stress burden. Practitioners collect a small hair sample from the posterior vertex of the scalp.

Metric

Hair Cortisol Concentration is quantified by collecting a hair sample, typically a 3-centimeter segment closest to the scalp, representing about three months of cortisol exposure. The hair is washed to remove external contaminants, then pulverized, and cortisol extracted. Analysis is commonly performed using highly sensitive laboratory techniques like liquid chromatography-tandem mass spectrometry (LC-MS/MS), with results expressed in picograms per milligram of hair.

Risk

Potential risks with interpreting Hair Cortisol Concentration results include confounding variables influencing measured levels, such as hair cosmetic treatments, medications, or external contamination. Hair cortisol reflects an integrated average, which may not capture acute stress responses or diurnal variations, potentially leading to misinterpretations if considered in isolation. Clinical decisions must integrate hair cortisol data with comprehensive patient history and other assessments.