Cortisol test: how to check your cortisol levels — blood, saliva, urine, and at-home kits

Short answer

A cortisol test measures cortisol in blood, saliva, or urine, and timing is part of the test. Cortisol normally peaks around 7–9 am and falls to its lowest point near midnight. A morning blood test, often followed by an ACTH stimulation test, checks for low cortisol. Late-night saliva, 24-hour urine, or a 1 mg overnight dexamethasone test screens for high cortisol.

Those are the first-line options named in the Endocrine Society guidelines for Cushing's syndrome and adrenal insufficiency (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125; J. Clin. Endocrinol. Metab., 2016, doi:10.1210/jc.2015-1710). Cortisol is also measured in hair, mostly in research. You can collect saliva or urine at home with a kit, but a clinician should choose the test and read the result. A wearable cannot measure cortisol at all — more on that, and on what our own Welltory data shows, in the wearables section below.

Cortisol tests at a glance

What does a cortisol test measure?

Cortisol is your body's main glucocorticoid stress hormone. Your adrenal glands release it under the control of the hypothalamic-pituitary-adrenal, or HPA, axis. If you want the full picture of what cortisol is and what it does, start there; this article focuses on how it is tested.

Most cortisol in your blood is not "free." About 80% is bound to a carrier protein called cortisol-binding globulin (CBG), and 10–15% is bound to albumin (J. Clin. Endocrinol. Metab., 2016, doi:10.1210/jc.2015-1710). That detail matters. A blood test measures total cortisol (bound plus free). Saliva and urine tests reflect the free, biologically active part. So anything that changes CBG can change a blood result without changing how much active cortisol you really have.

Cortisol also does not stay flat across the day. It follows a strong circadian rhythm: it is expected to be higher in the morning and lower late at night (MedlinePlus — Cortisol Test). In healthy people with a regular sleep schedule, blood cortisol starts to rise around 3–4 am, peaks at about 7–9 am, and then falls to very low levels by midnight (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). That daily swing is why the collection time is part of the test itself. A morning cortisol result and a midnight cortisol result answer different questions. Without the sampling time, the number loses much of its meaning.

Because cortisol tracks the sleep-wake cycle, researchers treat its timing as a biological signal, not just a single "stress level." A 2025 review of cortisol detection methods framed cortisol measurement around its role in evaluating circadian-rhythm disruption (Int. J. Molecular Sciences, 2025, PMC12470794). The pattern matters.

What are the different types of cortisol tests?

There are five main ways to test cortisol. Each one answers a slightly different question, so doctors pick the test based on whether they suspect too much cortisol, too little, or a disrupted daily rhythm.

Cortisol blood test

A cortisol blood test is a standard blood draw. It is often done in the morning, when cortisol should be near its daily high point. Your provider will usually schedule it early for exactly that reason, and you may be asked to avoid vigorous exercise the day before (MedlinePlus — Cortisol blood test). Sometimes clinicians repeat blood testing later to see whether cortisol falls as expected.

Blood cortisol is a snapshot. That can be useful, especially when a clinician is checking for low cortisol or planning an ACTH stimulation test. But one blood draw cannot show the whole daily curve. Research on HPA-axis conditions notes that "findings from blood cortisol measurements remain inconsistent" (Front. Cell. Infect. Microbiol., 2026, doi:10.3389/fcimb.2025.1690698), which helps explain why clinicians often use saliva, urine, or dynamic testing depending on the question.

A random daytime blood cortisol is also a poor way to look for high cortisol. The Endocrine Society guideline specifically recommends against using a random serum cortisol to test for Cushing's syndrome, because normal daytime values vary so much (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125).

Cortisol saliva test and late-night salivary cortisol

A cortisol saliva test measures the free, biologically active fraction of cortisol. Free cortisol in the blood is in balance with cortisol in saliva, so saliva tracks blood changes closely (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). It is noninvasive, so it works well when samples need to be collected at home or at several points across the day.

Late-night salivary cortisol is commonly used when clinicians need to know how to test for high cortisol, because it targets the time when cortisol should be low. It is one of the recommended first-line screening tests for Cushing's syndrome (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). Most clinicians ask for samples on two separate evenings between 11 pm and midnight, either by drooling into a tube or by chewing a cotton swab for 1–2 minutes. The sample is stable at room or fridge temperature for several weeks and can be mailed to a lab (J. Clin. Endocrinol. Metab., 2008).

If cortisol stays high late at night, that can support a work-up for Cushing's syndrome — but it does not diagnose it by itself. Losing the normal late-night dip is a consistent finding in people with Cushing's syndrome, which is exactly what this test looks for.

Multi-point saliva testing can also show the daily curve. In one HPA-axis study, "salivary cortisol (SC) profiling may provide a more accurate assessment of HPA activity" (Front. Cell. Infect. Microbiol., 2026, doi:10.3389/fcimb.2025.1690698) than a single blood draw. In a clinical trial, "Salivary cortisol was measured at six points during the day" (J. Gerontol. B, 2026, PMC12795603) to capture more of that pattern.

24-hour urine free cortisol test

A 24-hour urinary free cortisol (UFC) test asks you to collect all urine over 24 hours. Instead of catching one moment, it estimates how much free cortisol your body excreted across a full day.

Clinicians use it as one of the core screening tests when Cushing's syndrome is suspected, and the guideline recommends at least two separate collections because cortisol output in Cushing's can vary from day to day (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). Because the test depends on a complete collection, missing urine can make the result misleading. Labs often check creatinine in the same sample to confirm the collection was complete.

Urinary cortisol is a well-established analyte in research. One study specifically tested "whether urinary cortisol can be reliably measured after long-term storage" (Am. J. Human Biology, 2026, doi:10.1002/ajhb.70249), underscoring why urine has remained a practical cortisol sample type.

Dexamethasone suppression test

In a dexamethasone suppression test, a clinician directs you to take dexamethasone, and cortisol is measured afterward. Dexamethasone is a synthetic glucocorticoid. In a normally responding HPA axis, it should signal the body to reduce cortisol production.

In the standard 1 mg overnight test described in the Endocrine Society guideline, 1 mg of dexamethasone is usually taken between 11 pm and midnight, and blood cortisol is measured between 8 and 9 am the next morning (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). A longer 2-day low-dose version also exists.

If cortisol does not suppress as expected, the result can point toward Cushing's syndrome and usually leads to more testing (J. Clin. Endocrinol. Metab., 2008). This is not a self-test. It involves a prescription medication, exact timing, and guideline-based interpretation that must be set by a clinician — never self-adjusted. Some medications speed up or slow down how the body clears dexamethasone, which can distort the result, so your clinician needs your full medication list.

Hair cortisol

Hair cortisol is different. It does not tell you what your cortisol was this morning. It reflects exposure over a longer window.

Researchers describe it this way: "Hair cortisol concentration (HCC) reflects cumulative cortisol exposure and may provide clinically relevant information beyond single-time-point assessments" (Front. Endocrinol., 2026, doi:10.3389/fendo.2026.1765179). Another review states that "hair cortisol is suitable for identifying chronic changes and prolonged elevations in cortisol levels" (Int. J. Molecular Sciences, 2025, PMC12470794). For now, hair cortisol is mostly a research or specialist tool, not a routine same-day diagnostic test.

When is the best time to take a cortisol test?

The most important variable in a cortisol test is time of day. The right time depends on what your clinician is looking for:

• Checking for low cortisol: an early-morning blood test, usually around 8 am, close to the daily peak of 7–9 am (MedlinePlus — Cortisol blood test; J. Clin. Endocrinol. Metab., 2008).

• Checking for high cortisol: a late-night saliva sample between 11 pm and midnight, when cortisol should be at its lowest (J. Clin. Endocrinol. Metab., 2008).

• Dexamethasone test: tablet at 11 pm to midnight, blood draw at 8–9 am the next day.

• 24-hour urine: your provider tells you when to start. You flush the first urine, note the time, then collect everything for the next 24 hours and keep it cold (MedlinePlus — Cortisol Test).

• Cortisol awakening response: timed saliva samples right after you wake up.

Cortisol usually rises after waking, increases further during the early waking period — the cortisol awakening response — and then declines through the day toward a late-night low (MedlinePlus — Cortisol Test). The awakening response is a sharp rise over the first 30–45 minutes after waking (Psychoneuroendocrinology, 2016, doi:10.1016/j.psyneuen.2015.10.010). A cortisol awakening response test uses timed saliva samples soon after waking to study that early rise. Expert consensus guidelines stress that the result depends on following the schedule exactly, starting from the moment you wake; even a short delay can skew it (Psychoneuroendocrinology, 2016). Follow your kit's or clinician's exact sampling window.

Two things can easily distort the rhythm.

First, shift work and disrupted sleep can move or flatten the cortisol curve. A study of nurses examined "the effects of single versus double-shift work schedules on salivary cortisol concentrations among nurses" (Nursing Open, 2026, doi:10.1002/nop2.70495). Sleep-focused research also lists "Salivary cortisol (HPA axis)" (Nature & Science of Sleep, 2025, PMC12525384) among candidate markers of stress-related sleep disruption. If you work nights, read how your body clock and sleep timing interact — and tell your clinician, because the Endocrine Society notes the late-night saliva test may not be appropriate for shift workers or people with variable bedtimes, and the timing may need to match your actual sleep time (J. Clin. Endocrinol. Metab., 2008).

Second, illness and other stressors can change the daily pattern. HPA-axis research in Long COVID reports that "LC patients exhibit a disrupted diurnal cortisol rhythm" (Front. Cell. Infect. Microbiol., 2026, doi:10.3389/fcimb.2025.1690698).

The practical point is simple: follow the collection schedule exactly, and record the real sampling time. If your kit says late night, morning, or multiple points, those times are not optional details.

What are normal cortisol levels by time of day?

There is no single "normal cortisol level." What counts as normal depends on the time of day, the type of sample, the test protocol, and the lab's assay. Always compare your number with the reference range printed on your own lab report. For a broader look at how levels move through the day, see our guide to cortisol hormone levels.

The figures below are reference points from official and guideline sources. They are lab-dependent and are not for self-diagnosis.

A few notes make this table easier to read:

• Morning low values. When stimulation testing isn't available, the adrenal insufficiency guideline suggests that a morning cortisol below 140 nmol/L (5 mcg/dL), together with a high ACTH level, is a preliminary sign of adrenal insufficiency — pending confirmation (J. Clin. Endocrinol. Metab., 2016).

• Newer assays use different cut-offs. The 18 mcg/dL threshold came from older assays. A 2021 study of 110 patients recommended a lower cut-off of 14–15 mcg/dL with newer, more specific assays, to avoid false-positive diagnoses (J. Endocr. Soc., 2021, doi:10.1210/jendso/bvab022).

• Different labs, different numbers. The Cushing's guideline warns that a single sample measured with different assays "may be quite different," and results near a cut-off should be repeated (J. Clin. Endocrinol. Metab., 2008).

How accurate are cortisol tests?

When they're done the right way, in the right people, the main screening tests for high cortisol are quite accurate. The key words are "the right way" and "the right people."

A systematic review and meta-analysis for the Endocrine Society pooled 27 studies of 8,631 patients suspected of Cushing's syndrome; 794 of them (9.2%) turned out to have it (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0139). The three main tests performed similarly:

• 24-hour urine free cortisol: a positive result was about 10.6 times more likely in people with Cushing's than without it.

• Late-night salivary cortisol: about 8.8 times more likely.

• 1 mg overnight dexamethasone test: about 16.4 times more likely.

The authors noted an important limit: these results came from referral clinics with many confirmed cases, and "their performance in usual clinical practice remains unclear" (J. Clin. Endocrinol. Metab., 2008). In plain terms, when fewer people being tested actually have the disease, more positive results are false alarms.

The guideline also summarizes individual tests. Across studies, late-night salivary cortisol showed 92–100% sensitivity and 93–100% specificity for Cushing's syndrome. For the overnight dexamethasone test, the 1.8 mcg/dL cut-off catches more than 95% of cases but has a specificity of about 80%, meaning some people without the condition test positive (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). That is why an abnormal first test is followed by a second, different test before anyone makes a diagnosis.

What can affect cortisol test results?

Many everyday factors can push a cortisol result up or down. Most false results come from these, not from lab errors.

Birth control pills and oral estrogen. Estrogen raises CBG, the protein that carries cortisol in the blood. Because blood tests measure total cortisol, the result goes up even though active cortisol may not. The Endocrine Society guideline reports false-positive dexamethasone test results in 50% of women taking the oral contraceptive pill, and suggests that estrogen-containing drugs be stopped for 6 weeks before testing wherever possible — a decision for your clinician, not something to do on your own (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). In a small study of 37 women, total blood cortisol was 67% higher in women taking oral estrogen than in women not taking estrogen, while salivary cortisol was similar across groups and transdermal estrogen showed no such rise (Clin. Endocrinol., 2007, doi:10.1111/j.1365-2265.2007.02784.x). Pregnancy raises CBG as well (J. Clin. Endocrinol. Metab., 2016).

Steroid medicines. Prednisone, hydrocortisone, and other glucocorticoids can distort results — and long-term use can suppress your own cortisol. The guideline asks clinicians to check for steroids taken by mouth, inhaled, injected into joints, or applied to the skin, including skin creams, bleaching agents, and herbal "tonics" that may contain them (J. Clin. Endocrinol. Metab., 2008). Never stop a steroid suddenly to "clean up" a test; low levels can happen if you stop the medicine suddenly (MedlinePlus — Cortisol Test).

Night shifts and irregular sleep. The circadian rhythm is blunted in many shift workers and in people with depression (J. Clin. Endocrinol. Metab., 2008). Short sleep matters too. In a lab study of healthy young men, one night of partial or total sleep loss raised evening cortisol the next day by 37% and 45%, and delayed the normal evening drop by at least an hour (Sleep, 1997, doi:10.1093/sleep/20.10.865).

Acute stress, illness, and pain. Hospitalization, surgery, pain, intense chronic exercise, poorly controlled diabetes, severe obesity, alcohol dependence, and depression can all raise cortisol without Cushing's syndrome (J. Clin. Endocrinol. Metab., 2008). Stress also shapes daily habits that loop back into your hormones — see how cortisol drives stress eating and emotional hunger.

Sample-specific traps.

• Saliva: licorice and chewing tobacco may falsely raise late-night salivary cortisol, smokers have higher readings (so avoid smoking on collection day), and steroid-containing lotions or oral gels can contaminate the swab (J. Clin. Endocrinol. Metab., 2008).

• Urine: drinking 5 liters or more of fluid a day can raise UFC, and moderate-to-severe kidney disease can make UFC falsely low (J. Clin. Endocrinol. Metab., 2008).

• Blood: critical illness, inflammation, or protein-losing kidney disease (nephrotic syndrome) can lower CBG or albumin and make total cortisol read low (J. Clin. Endocrinol. Metab., 2008; J. Clin. Endocrinol. Metab., 2016).

Other medicines. Some anti-seizure drugs, certain antibiotics, and other medicines change how quickly dexamethasone or cortisol is broken down (J. Clin. Endocrinol. Metab., 2008; J. Clin. Endocrinol. Metab., 2016). Bring a complete list of everything you take, including supplements.

How do you test cortisol levels at home?

You can collect a cortisol sample at home — in fact, the late-night saliva test is designed for it. A cortisol saliva test may be done at your provider's office or at home with a kit, using a swab or by spitting into a tube; your provider tells you when to collect (MedlinePlus — Cortisol Test). Some home kits collect urine instead.

If you are collecting at home, these steps help keep the result meaningful:

1. Confirm the exact time. Late-night kits usually ask for 11 pm to midnight; awakening kits ask for samples at set minutes after waking.

2. Collect on the days you're told. Late-night saliva is usually done on two separate evenings (J. Clin. Endocrinol. Metab., 2008).

3. Avoid known interferences on collection day: smoking, chewing tobacco, licorice, and steroid creams or gels near your mouth.

4. Write down the real time each sample was taken, plus anything unusual — a bad night, illness, a stressful day.

5. Don't change medications on your own before testing. Tell your provider about everything you use, including skin creams, and ask first (MedlinePlus — Cortisol Test).

6. Rest before sampling if you can, since stress and exercise can raise cortisol, and follow the kit's storage and shipping instructions (MedlinePlus — Cortisol Test).

Are at-home cortisol test kits accurate?

Search results for the best at home cortisol test often focus on brands, reviews, and convenience. That is not the same as clinical usefulness.

A home kit can be a legitimate way to collect a timed saliva or urine sample. Some kits use late-night saliva. Others use multiple samples across the day. That timing can matter because cortisol is rhythmic.

The accuracy of the collection is only half the story. The guideline cut-offs above were set with specific validated lab methods, and results from different assays "may be quite different" (J. Clin. Endocrinol. Metab., 2008). A home kit is only as reliable as the lab and assay behind it — ask which method it uses and whether its reference range matches the timing you collected.

What a home kit cannot do is diagnose you. It cannot interpret the result in the context of your medications, sleep schedule, illness, symptoms, pregnancy status, steroid exposure, or collection errors. An "instant cortisol test" or app result may feel definitive, but cortisol is too time-sensitive and context-sensitive for that.

If a home result is high, low, or confusing, use it as a reason to talk with a clinician. If a result is "normal" but the sample was collected at the wrong time — or on an unusually stressful, sleep-deprived, or sick day — it may not answer the question you thought it answered.

Commercial tests such as DUTCH or newer consumer brands sometimes appear in searches and community discussions, including Eli Health cortisol test reviews, Eli Health cortisol test Reddit threads, and similar review pages. Treat those as consumer information, not diagnostic evidence. Their clinical role should be discussed with a qualified clinician.

Can a wearable measure cortisol?

A wearable does not measure cortisol.

What it can track is a physiological proxy for stress load: resting heart rate and heart rate variability, or HRV, over time. That is a different signal. A lab cortisol test is a timed biological sample used for a specific clinical question. HRV and resting-HR trends show whether your body appears to be carrying sustained physiological strain day to day. If you are choosing a device for that, we've compared stress-monitoring devices side by side.

That distinction matters — and our own data underlines it. Among Welltory users who self-report high stress or burnout, day-to-day resting numbers look almost identical to everyone else: in a cohort of 2,213 Welltory users who self-report high stress or burnout (with quality wearable data), compared with 1,932 who do not, median resting heart rate (about 63 vs 62 bpm) and morning HRV score (3.09 vs 3.08) were statistically indistinguishable — the distributions overlapped roughly 92% (barely better than a coin-flip at telling the groups apart). In precise terms: morning HRV score 3.09 vs 3.08, resting heart rate 62.9 vs 61.6 bpm, AUC ~0.51, ~92% distribution overlap. In other words, a single resting-HR or HRV number can't flag who is carrying a high physiological stress load — which is precisely why a properly timed cortisol test, ordered and read by a clinician, remains the right tool for that question. These figures are observational, based on self-reported cohorts, and reported as anonymized, aggregated data; no individual user is identifiable.

Welltory is built around stress-load patterns, not around replacing a laboratory test. If your wearable data shows a persistent pattern — for example, higher resting heart rate together with suppressed HRV — it may help you describe what has been happening in your body and decide whether to raise the question of cortisol testing with a clinician. It is not a diagnosis.

What do high and low cortisol test results mean?

A cortisol result is a clue, not a verdict. An abnormal value tells a clinician what to investigate next. It does not, by itself, diagnose Cushing's syndrome, adrenal insufficiency, burnout, chronic stress, or "HPA-axis dysfunction."

High cortisol

Persistently high cortisol results can raise the question of Cushing's syndrome, especially when late-night salivary cortisol, 24-hour urinary free cortisol, or dexamethasone suppression testing is abnormal. The guideline recommends that anyone with an abnormal first test see an endocrinologist and do a second test; if both are abnormal, the next step is finding the cause (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125). For what persistently raised cortisol can feel like day to day, see high cortisol symptoms.

But a single high result can also reflect other factors: acute stress, illness, pregnancy, estrogen-containing medication, birth-control pills, or recent steroid exposure. That is why clinicians confirm with repeat and complementary tests before making a diagnosis.

Low cortisol

A low morning blood cortisol may raise concern for adrenal insufficiency, including Addison's disease, or for a pituitary-related problem. Clinicians often use ACTH stimulation testing to see whether the adrenal glands can respond appropriately; the adrenal insufficiency guideline calls this short corticotropin test the "gold standard" for diagnosis and recommends measuring ACTH alongside cortisol (J. Clin. Endocrinol. Metab., 2016, doi:10.1210/jc.2015-1710; MedlinePlus — Cortisol Test).

Severe low cortisol can become an emergency called adrenal crisis. The guideline says people with severe symptoms should be treated right away, before test results come back (J. Clin. Endocrinol. Metab., 2016).

Blunted or shifted rhythm

Sometimes single cortisol values fall inside a reference range, but the daily rhythm looks abnormal. A flattened diurnal slope or altered awakening response can reflect HPA-axis dysregulation seen in chronic stress states, shift-work disruption, or some chronic illnesses. That is one reason timed, multi-sample testing exists.

If your results are normal but you still feel wired, stressed, or run down, lifestyle levers such as sleep timing, movement, and recovery are worth a look — our guide on how to lower cortisol covers the evidence.

Interpretation of abnormal results is a clinical act. This section describes what tests may point toward, not how to self-diagnose. Exact thresholds and diagnostic algorithms come from clinical guidelines and clinician interpretation.

Can a cortisol test diagnose adrenal fatigue?

No. "Adrenal fatigue" is not a recognized medical diagnosis, and no cortisol test can confirm it.

The idea behind adrenal fatigue is that long-term stress "wears out" the adrenal glands, causing tiredness, poor sleep, and cravings. The Endocrine Society states that no scientific proof supports adrenal fatigue as a true medical condition, that there is no test that can detect it, and that blood or saliva tests sold for it are not based on good scientific studies (Endocrine Society — Adrenal fatigue, 2022). Its concern is practical: if you are told you have adrenal fatigue, the real cause of your symptoms may be missed.

A 2016 systematic review screened 3,470 articles and included 58 studies that measured cortisol in people with fatigue or burnout. The most common tests were waking cortisol, the cortisol awakening response, and salivary cortisol rhythm. Results were conflicting almost across the board, and the authors concluded there is no substantiation that adrenal fatigue is an actual medical condition (BMC Endocr. Disord., 2016, doi:10.1186/s12902-016-0128-4).

That doesn't mean your exhaustion isn't real. Fatigue, broken sleep, and low drive have many real causes — including true adrenal insufficiency, thyroid problems, anemia, sleep apnea, depression, and burnout. A clinician can use proper tests to look for them. If a lower sex drive is part of the picture in midlife, our piece on cortisol and a frozen libido in your 40s explains how stress hormones may play in.

When should you ask your doctor for a cortisol test?

Cortisol testing is not a routine screening test for everyone. The Cushing's guideline recommends against testing people who don't have compatible features, because false positives lead to unnecessary follow-up (J. Clin. Endocrinol. Metab., 2008, doi:10.1210/jc.2008-0125).

Signs that may justify testing for high cortisol include several progressive features at once — especially the ones that best point to Cushing's syndrome: easy bruising, a flushed, reddish face, weakness in the muscles around the hips and shoulders, and reddish-purple stretch marks wider than 1 cm. Unusual findings for your age, such as osteoporosis or high blood pressure in a young adult, or an adrenal lump found on a scan, are also reasons to test (J. Clin. Endocrinol. Metab., 2008). Common features like weight gain, fatigue, and depression overlap heavily with everyday life and are less specific on their own. If weight around your middle is what's worrying you, read does cortisol cause weight gain? before assuming it's a hormone problem.

Signs that may justify testing for low cortisol include unexplained low blood pressure, dehydration, low sodium or high potassium on blood tests, fever, abdominal pain, and darkening of the skin (J. Clin. Endocrinol. Metab., 2016, doi:10.1210/jc.2015-1710).

Cortisol testing is usually ordered by a primary-care clinician, an endocrinologist, or another qualified healthcare professional. The right test depends on the clinical question.

You may be asked to:

• collect saliva at a precise late-night time;

• collect all urine over 24 hours;

• come in for an early-morning blood draw;

• complete dexamethasone suppression testing under clinician direction;

• complete ACTH stimulation testing if low cortisol or adrenal insufficiency is suspected.

The most common ways a cortisol test becomes misleading are practical: the sample is collected at the wrong time, the 24-hour urine collection is incomplete, you are acutely ill or sleep-deprived, or an interfering medication was not handled according to your clinician's instructions.

If your symptoms are real but one test is normal, that does not automatically mean "nothing is wrong." It may mean your clinician needs a different test, a repeat test, or a better-timed sample. If you ever have severe symptoms such as fainting, chest pain, or a rapid irregular heartbeat, seek immediate medical attention rather than waiting for a test.

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