Guides
Everything about testing cortisol
45 guides, written from the research and from clinical guidance, with every figure referenced. Start with the hair test if you want to know where your cortisol has been for the last three months.
Hair cortisol testing
How a hair test works, how accurate it is, how to take a sample and what your result means.
- The hair cortisol testHow hair records cortisol, what the research shows about accuracy, how to take a sample and what a hair test is not for.
- How hair cortisol testing worksHow cortisol enters hair, how growth rate sets the time window, why older hair reads lower and how laboratories measure it.
- Is hair cortisol testing accurate?How hair cortisol compares with repeated saliva and urine, how consistent it is, its accuracy for Cushing's and where it falls short.
- Hair vs blood cortisol testBlood shows one moment, hair shows months. Timing, the needle, the pill and lab methods compared, and when blood is the right test.
- Hair vs saliva cortisol testSaliva catches moments and the daily curve; hair gives a months-long average. State versus trait, the awakening response and Cushing's.
- Hair vs urine cortisol testOne day of urine or three months of hair: variability, how well the two agree, and where each test fits, including Cushing's.
- Hair cortisol vs the DUTCH testA detailed one-day urine profile or a three-month average: what the DUTCH test measures, its evidence, and how it compares with hair.
- At-home cortisol testsHair, finger-prick blood, saliva and urine kits: what each home test measures, timing and medicine pitfalls, and when to see a doctor.
- How much does a cortisol test cost?UK and US cortisol test prices as of October 2026, hidden fees, the cost of a reliable answer, and what is not worth paying for.
- How to take a hair sampleWhere to cut, how much to take, why the cut must be close to the scalp, and the common mistakes to avoid.
- How often to test cortisolSensible retest intervals, why hair results compare well over time, timing a test after a change, and why spot tests need repeats.
- Hair cortisol results explainedWhat pg/mg means, why ranges differ between laboratories, what high or low results can reflect and when to see a doctor.
- Segmental hair cortisol analysisHow hair segments map to months, why washout limits the look-back to about six months, and how timelines are used in Cushing's.
- Hair cortisol testing with dyed or treated hairHow dye, heat, washing, sunlight, storage and grey hair affect a hair cortisol result, and how to take a fair sample.
Understanding cortisol
What cortisol does, what normal looks like, and what pushes it up or down.
- What is cortisol?What cortisol does, how the HPA axis and ACTH control it, free and bound cortisol, and the four ways to measure it.
- Normal cortisol levelsTypical ranges for blood, saliva, urine and hair cortisol, the NICE thresholds for low cortisol, and why your own lab's range counts.
- Cortisol daily rhythmThe daily cortisol curve, the awakening response, sleep loss, shift work and why timing matters for every test except hair.
- Cortisol and stressHow acute and chronic stress change cortisol, what hair studies show, and why how stressed you feel and your cortisol often differ.
- How to lower cortisolMeditation, exercise, sleep, alcohol and diet: what lowers cortisol in trials, what is unproven, and how to check it is working.
- Cortisol and sleepThe nightly low, the morning rise, and what sleep loss, shift work and insomnia do to your cortisol.
- Cortisol and weightHair studies link higher long-term cortisol with BMI and waist size, but the effect is small. What it means, and when to see a doctor.
- Cortisol and exerciseWhy hard sessions raise cortisol, how regular moderate exercise lowered it over a year, and what very heavy training does.
- Caffeine, alcohol, food and cortisolWhat coffee, alcohol, meals and dieting do to cortisol, and how to prepare for blood, saliva and hair cortisol tests.
- Cortisol, anxiety and depressionWhat hair cortisol studies show in depression, anxiety and PTSD, why results conflict, and where to get help.
- Adrenal fatigueWhy adrenal fatigue is not a recognised condition, what really causes the same symptoms, and how those causes are tested.
Blood, saliva and urine tests
The single-moment tests doctors use, what each one can and cannot tell you, and how to prepare.
- The blood cortisol testHow a morning blood cortisol test works, how to prepare, typical ranges and NICE thresholds, and what can skew the result.
- The saliva cortisol testDaily profiles, the waking rise and the late-night test for Cushing's: how saliva testing works, how to collect and what spoils a result.
- The 24-hour urine cortisol testHow to collect a 24-hour urine sample, what urinary free cortisol shows, typical ranges, and why doctors ask for more than one.
- The DUTCH testHow the dried urine DUTCH test is collected, what it reports, the evidence behind it and how it compares with standard cortisol tests.
- The dexamethasone suppression testThe overnight 1 mg dexamethasone test for Cushing's syndrome and adrenal incidentalomas: how it is done, the 50 nmol/L cut-off and pitfalls.
- The Synacthen testWhat happens in a short Synacthen (ACTH stimulation) test, how to prepare, why cut-offs depend on the laboratory and what results mean.
- Getting a cortisol test from your doctorWhen doctors test cortisol, which tests they use, how to prepare, what to ask and what happens after the result.
Symptoms and conditions
Signs of high and low cortisol, and how Cushing's syndrome and adrenal insufficiency are tested for.
- High cortisol symptomsThe signs of too much cortisol, the most common causes, everyday rises that are normal, and when symptoms need a doctor.
- Low cortisol symptomsThe signs of low cortisol, its causes including stopping steroids, what an adrenal crisis looks like and how doctors diagnose it.
- Testing for Cushing's syndromeThe first-line tests for Cushing's syndrome, their cut-offs, why they are repeated, and what research on hair cortisol shows.
- Testing for Addison's diseaseHow Addison's disease is diagnosed with morning cortisol and Synacthen tests, adrenal crisis and sick-day rules, and why hair cannot help.
- Cortisol and hair lossStress, shedding and cortisol: what the research shows, what Cushing's does to hair, and taking a hair sample when hair is thinning.
- Burnout and cortisolWhat studies of hair cortisol show about burnout, work stress and shift work, why no test diagnoses burnout, and what can help.
- Cortisol and heart healthWhat hair cortisol studies show about heart disease, blood pressure and metabolic syndrome, and why association is not cause.
Cortisol and your life
Cortisol in menopause, pregnancy, sport, shift work and later life.
- Cortisol and the menopauseHow cortisol changes around the menopause, what HRT tablets do to a blood test, and what hair and blood tests can tell you.
- Cortisol, fertility and pregnancyWhy cortisol rises in pregnancy, why blood results mislead, what hair shows, and what is known about stress and fertility.
- Cortisol in athletesHow training intensity and volume affect cortisol, what hair shows in athletes, and why no test diagnoses overtraining.
- Cortisol and shift workWhat shift work does to the cortisol rhythm, why standard tests are hard to time on shifts, and what a hair test can and cannot show.
- Cortisol and ageingHow the cortisol rhythm changes with age, what hair studies of older adults show, and what the links with disease do and do not mean.
- Cortisol in men and womenSex differences in the daily rhythm and in hair cortisol, and how the pill, HRT and pregnancy affect blood, saliva and hair tests.