When is Cortisol Labor actually useful?

The provided context does not contain specific information about cortisol lab testing. In general, cortisol measurement is useful for diagnosing adrenal insufficiency (Addison's disease), Cushing's syndrome, and assessing adrenal function under stress. A salivary cortisol day profile (multiple time points) is more reliable than a single blood draw due to circadian variation. A single morning cortisol can serve as a screening test but is often insufficient. Important: cortisol is affected by stress, sleep deprivation, medications (e.g., corticosteroids, birth control pills), and time of day. Without a medical indication and professional interpretation, a home test has limited value. Evidence is based on clinical practice, not on the provided sources.