What should I know about Cortisol Test?

A cortisol test measures levels of the stress hormone cortisol, typically in blood, saliva, or urine. It is used to diagnose adrenal disorders such as Cushing's syndrome (elevated) or Addison's disease (low). A DNA test can identify genetic variants in genes like NR3C1 or FKBP5 that influence cortisol regulation, but it cannot provide your current cortisol levels. The predictive value of such genetic markers is modest; lifestyle factors (sleep, stress, diet) have a much larger impact. Many commercial tests overstate the clinical utility. A normal cortisol level does not rule out stress-related issues, as the daily rhythm and reactivity matter more than a single measurement. Be cautious of tests offered without medical indication—they may cause unnecessary worry. Evidence: mechanistic to human-moderate.