wie kann man den cortisolspiegel messen — what can you do yourself?

Cortisol can be measured in saliva, blood, urine, or hair. For self-testing at home, saliva kits (often as a diurnal profile with 4–5 collection times) or dried blood spot kits are available. These measure free, biologically active cortisol. However, cortisol follows a strong circadian rhythm (high in the morning, low at night). A single measurement is nearly useless; a profile over the day is needed. The accuracy of home kits varies, and many lack clinical validation. Stress, poor sleep, or medications can skew results. Without medical guidance, do not start any therapy (e.g., supplements) based on self-tests. The evidence for reliable self-measurement is weak—most research uses lab-based assays. If you have symptoms like chronic fatigue or weight changes, see a doctor for proper diagnostics (e.g., dexamethasone suppression test).