wie kann man cortisol messen — what does this mean exactly?

Cortisol can be measured in blood, saliva, urine, or hair. Blood and saliva tests capture current levels and are used to diagnose Cushing's syndrome or Addison's disease. Saliva is convenient for circadian profiling (multiple samples across the day). 24-hour urine collection measures free cortisol excretion. Hair cortisol reflects long-term exposure (weeks to months) but is mainly used in research. Important: A single measurement is rarely meaningful due to diurnal variation and external factors (stress, sleep, medication). Interpretation must be done by a physician. DNA tests (e.g., NR3C1, BDNF variants) do not measure cortisol levels; they assess genetic predispositions that may slightly influence stress response, but effect sizes are small and not diagnostic. Evidence: human-established for blood/saliva/urine; hair cortisol is still emerging. Caveat: Do not self-diagnose; consult a doctor for abnormal cortisol symptoms.