wie kann ich cortisol messen — what are common causes?

Cortisol can be measured in blood, saliva, urine, or hair. Blood measures total cortisol, saliva reflects free (active) cortisol, urine captures 24-hour excretion, and hair shows long-term average. Common causes of high cortisol include chronic stress, Cushing's syndrome, certain medications (e.g., corticosteroids), and psychological strain. Low cortisol may indicate adrenal insufficiency (Addison's disease) or pituitary disorders. Important: Cortisol follows a strong circadian rhythm (high in the morning, low at night) and is affected by acute stress, sleep deprivation, or food intake. A single measurement is rarely diagnostic; multiple measurements or dynamic tests (e.g., dexamethasone suppression test) are often required. Evidence for measurement methods is solid (clinical practice), but interpretation requires medical expertise. Note: At-home tests can provide clues but should not replace professional diagnosis.