Risks and limits of Cortisol Labor

Cortisol lab tests (blood, saliva, urine) have significant limitations: values fluctuate with circadian rhythm, acute stress, sleep deprivation, diet, and medications. A single measurement is rarely meaningful; multiple timed samples (e.g., morning, evening) or a dexamethasone suppression test are needed. Direct-to-consumer DNA tests for cortisol-related genes (e.g., NR3C1, FKBP5) provide only mechanistic clues, not clinical diagnoses. Risks include overinterpretation leading to unnecessary anxiety or self-treatment (e.g., supplements). For suspected true cortisol dysregulation (Cushing, Addison), consult an endocrinologist. Evidence: mostly population-based, not individually diagnostic.