Severe weakness, vomiting, confusion or fainting in someone with a known adrenal problem needs emergency care. Call 911.
The sections below work through each test in turn, what it can show, and what no single number can tell you on its own.
A single cortisol value shows how much of the main glucocorticoid hormone was circulating at the exact moment the needle went in, and very little beyond that. Cortisol follows a daily rhythm, rising to a peak shortly after waking and drifting down through the evening, so the same healthy person can produce a high-normal number at 8 a.m. and a low one at 10 p.m. with nothing wrong at all. The cortisol marker page covers what the hormone is, how it is measured and how a result is read in detail. For the rest of this guide the more useful question is a different one, which is what tests get built around that number to work out whether the adrenal glands themselves are the problem.
Adrenal testing is usually ordered when a specific pattern of symptoms or routine blood results points toward too little or too much adrenal hormone, not as a general wellness sweep.
The underactive pattern tends to build slowly and quietly. Fatigue that rest does not fix, unintended weight loss, poor appetite, nausea, light-headedness on standing, low blood pressure and a pull toward salty food are the features that commonly raise suspicion of primary adrenal insufficiency 1. Darkening of the skin in palm creases, scars and gums is associated with primary adrenal insufficiency, because the pituitary signal that drives the adrenal glands also acts on pigment cells 1.
The overactive pattern looks different. Weight gain concentrated around the trunk and face, thin skin that bruises easily, wide coloured stretch marks, weakness in the thigh and shoulder muscles, rising blood sugar and rising blood pressure can all prompt a clinician to ask whether cortisol output is too high. Blood pressure that stays stubbornly high despite several medications, especially alongside a low potassium, can prompt testing of the hormone that controls salt balance instead.
There are two other common triggers. One is an adrenal nodule spotted by accident on a scan ordered for something else, which raises the question of whether it is producing hormone. The other is known pituitary disease, because the pituitary is what tells the adrenal glands to work. In all of these situations the point of testing is to replace a guess with a measurement, and the clinician decides which measurements answer the question being asked.
An adrenal workup is a sequence rather than a single panel, starting with a morning cortisol and widening only as far as the first results require.
| Test | What it measures | What it is generally used for |
|---|---|---|
| Morning serum cortisol | Total cortisol in blood at the daily peak | First-line screen for underactive adrenal function |
| Plasma ACTH | The pituitary signal telling the adrenal cortex to make cortisol | Separating an adrenal problem from a pituitary one |
| ACTH stimulation test | Cortisol response after synthetic ACTH is given in clinic | Confirming or ruling out adrenal insufficiency when a single value is borderline |
| DHEA-S | An adrenal androgen precursor that is stable through the day | Background on overall adrenal cortex output |
| Aldosterone and renin | The hormone pair that governs sodium, potassium and blood pressure | Checking the salt-balancing layer of the adrenal cortex |
| Sodium, potassium, glucose | Everyday chemistry downstream of adrenal hormones | Early clues that often appear before hormone testing is ordered |
| Late-night salivary cortisol or 24-hour urinary free cortisol | Cortisol output across a window rather than a moment | Used when the question is cortisol excess |
| Adrenal antibodies or imaging | Immune markers or gland structure | Working out the cause once a deficiency is established |
Not every row belongs in every workup. Someone being checked for too little cortisol follows a very different path from someone being checked for too much, and ordering the whole table at once tends to produce confusing results rather than clearer ones.
Morning timing matters because cortisol peaks shortly after waking, so an early sample is the one moment when a genuinely low result is hard to explain away. A low value taken in the afternoon tells you almost nothing, since low is normal then.
Most protocols use a sample drawn in the first hour or two after waking, conventionally around 8 a.m. for someone on a standard sleep schedule. Research suggests that a morning cortisol measurement works well as the first screening step for adrenal insufficiency, with very low values making the condition much more likely and comfortably high values making it unlikely enough that many people need nothing further 2.
The cut-off used is not universal. Research suggests that newer cortisol assays read lower than the older ones the classic thresholds were built on, so the number on your report has to be interpreted against the thresholds your own laboratory uses 3. This is one reason a result that looks alarming when compared against a number found online can look ordinary to the clinician reading the actual report.
Practical points follow from this. Night-shift workers have a shifted rhythm, so the draw is timed to their waking hour rather than the clock. A sample taken after a stressful commute, a hard workout or a sleepless night is still valid, but worth mentioning to whoever reads it.
The ACTH stimulation test, also called the short ACTH test, checks whether the adrenal glands can respond when they are directly told to make cortisol, which a single resting measurement cannot establish.
The sequence is simple from the patient side. Blood is drawn for a baseline cortisol, synthetic ACTH is given by injection in the clinic, and blood is drawn again at set intervals afterwards to see how far cortisol climbs. Healthy adrenal glands respond briskly. Glands that are damaged, or that have been idle for a long time because the pituitary signal was missing, respond weakly or not at all.
The Endocrine Society clinical practice guideline on primary adrenal insufficiency regards this test as the standard way to confirm the diagnosis when a morning cortisol leaves the question open 4. Published guidance for adults describes the same stepwise approach, with the stimulation test used to settle borderline baseline values rather than to replace them 5.
A few things are worth knowing in advance. The test takes roughly an hour of sitting in a clinic rather than a quick walk-in draw. It is ordered and supervised by a clinician, never self-arranged, and the dose and timing of the injection are decisions a licensed provider makes. A normal response is reassuring about the adrenal glands but does not rule out every pituitary problem, which is why the full picture includes the ACTH level itself.
Pairing ACTH with cortisol tells you where in the chain the problem sits, which is the single most useful piece of information an adrenal workup produces.
The logic runs in one direction. The pituitary releases ACTH, ACTH instructs the adrenal cortex, and the cortisol produced feeds back to quieten the pituitary. When the adrenal glands themselves are failing, cortisol is low while ACTH climbs, because the feedback brake has come off. When the pituitary or hypothalamus is the problem, cortisol is low and ACTH is low or inappropriately normal, because the instruction was never sent loudly enough.
Diagnostic algorithms built around this pairing use ACTH as the branch point that separates primary adrenal causes from pituitary causes, which then directs the next round of tests toward adrenal antibodies and imaging in one direction, or pituitary assessment in the other 6.
ACTH is a fussy sample. It degrades quickly, so it usually needs a chilled tube handled promptly, drawn at the same morning sitting as the cortisol. A result from a mishandled sample can be misleading, which is one reason this test is ordered through a clinic rather than picked off a menu. As with everything here, the observation is a direction of travel, not a label, and the pattern needs a clinician to read it.
Aldosterone and renin assess a different layer of the adrenal cortex, the one that manages sodium, potassium, fluid volume and blood pressure rather than the stress response.
Renin comes from the kidney and rises when blood volume or pressure falls. Aldosterone comes from the outer layer of the adrenal cortex in response to that signal and tells the kidney to hold sodium and shed potassium. Reading them as a pair shows whether the adrenal side is responding appropriately to the kidney side, or acting independently of it.
In primary adrenal insufficiency the outer layer is often affected along with the cortisol-producing layer, which is why the Endocrine Society guideline includes measurement of renin and aldosterone when working out whether salt-regulating function is also impaired 4. The classic laboratory signature is a high renin sitting next to a low or unimpressive aldosterone.
The pair is also used in the opposite direction. When the suspicion is too much aldosterone, laboratories report the ratio of aldosterone to renin, because an aldosterone that is high while renin is suppressed suggests the gland is working on its own schedule rather than following the kidney. That testing has strict preparation rules around posture, timing and several common medications, so it is set up by the clinician ordering it rather than arranged independently.
DHEA-S is the most abundant steroid the adrenal cortex produces, and it is useful mainly as a stable, big-picture read on adrenal output rather than as a stand-alone test for adrenal disease.
Unlike cortisol, dhea s does not swing through the day. Its sulfated form clears slowly, so a sample drawn at 2 p.m. is as meaningful as one drawn at 8 a.m., which makes it convenient and reproducible. In adults it comes overwhelmingly from the adrenal glands, so the number reflects what that tissue is doing rather than what the ovaries or testes are doing.
Two caveats keep it in proportion. The first is age. DHEA-S peaks in early adulthood and declines steadily from there, so a result has to be compared against an age-matched and sex-matched range before it means anything. A number that would be unremarkable at sixty would stand out at twenty-five.
The second is specificity. A low DHEA-S on its own is not a diagnosis and does not establish adrenal insufficiency, which still requires cortisol, ACTH and usually stimulation testing. A high DHEA-S in someone with acne, scalp hair thinning or irregular cycles can point a clinician toward an adrenal source of androgen worth investigating further. In both directions the right response is the same, which is to bring the result to a clinician who can see it next to the rest of the panel.
Standard chemistry often flags an adrenal problem before anyone orders a hormone test, because adrenal hormones control electrolytes and glucose.
The pattern to know is a low sodium sitting next to a high potassium. Without enough of the salt-regulating hormone, the kidney lets sodium go and holds potassium back. Low sodium at presentation is associated with primary adrenal insufficiency and is one of the findings that should prompt a clinician to consider it 1.
Other supporting clues can appear in the same panel. Blood glucose running low, particularly after a long gap without food, fits a shortage of the hormone that defends blood sugar. Mild anaemia and a raised eosinophil count turn up in some cases. None of these is specific on its own, and all of them have far more common explanations, which is exactly why they are clues rather than answers.
These findings carry more weight when someone is acutely unwell. Guidance written for emergency clinicians describes adrenal crisis as a presentation where low blood pressure, vomiting, confusion and electrolyte disturbance appear together and require immediate action rather than an outpatient workup 7. That is the situation the emergency line at the top of this page refers to. A stable person with a mildly unusual electrolyte result is in a completely different situation, and the next step there is a conversation with a clinician, not an emergency department.
Morning serum cortisol is reported against a wide reference range, because the hormone normally varies a great deal between people and across the day.
| Marker | Typical lab reference range | FitScript optimal range |
|---|---|---|
| Morning serum cortisol | 6 to 23 µg/dL | 10 to 18 µg/dL |
These are typical lab reference values, and ranges vary by laboratory, assay, age, sex and the exact time the sample was taken, so your own report is the version that counts. FitScript's optimal range is an optimization target rather than a diagnostic cut-off, and a value inside or outside it is not a diagnosis of anything.
Ranges for the other adrenal markers are deliberately left out here. ACTH, aldosterone, renin and DHEA-S are measured by methods that differ enough between laboratories, and vary enough with age, sex, posture and sample handling, that quoting a single number would be more misleading than helpful. Read each one against the range printed next to it on your own report, and let the clinician who ordered it interpret the combination rather than any single line.
A single out-of-range cortisol is an observation that narrows the possibilities, not a verdict on the glands.
A low morning value may reflect genuinely reduced adrenal output, a weak pituitary signal, a sample drawn later in the day than intended, or a shifted sleep schedule that moved the natural peak. The sensible next step is repeat testing at the right hour with ACTH measured at the same time, and a stimulation test if the picture stays ambiguous 2. A low value is suboptimal information rather than a finished answer, and it is worth discussing with a clinician rather than acting on alone.
A high morning value may reflect ordinary physiology more often than disease. Acute illness, pain, recent intense exercise, a stressful draw, pregnancy and anything that raises the carrier protein cortisol travels on can all push the total number up without the active hormone being excessive. When genuine cortisol excess is the question, clinicians do not rely on a morning serum level at all and move to tests that sample a longer window.
In both directions the sequence is the same. Note what the value shows, consider what it may reflect, then take it to a clinician who can read it against your symptoms, your other markers and the time the blood was drawn. Values far outside the printed range, particularly alongside symptoms, are worth discussing with a clinician promptly rather than at the next routine visit. No result here should ever be ignored, and none of it amounts to a diagnosis.
Plenty, which is why interpretation depends on context the laboratory does not see.
Timing is the biggest factor, since the same gland produces very different numbers across a day. Sleep pattern matters next, because the peak follows your waking time rather than the clock, and shift work moves it. Acute illness, injury, surgery and even a difficult needle stick raise cortisol by design, since that is what the hormone is for.
Carrier proteins matter more than most people expect. Standard assays measure total cortisol, most of which is bound to a transport protein rather than active, so anything that raises or lowers that protein shifts the total without shifting the usable amount. Pregnancy is the most common example.
The assay itself contributes. Research suggests that modern cortisol assays produce systematically different values from older methods, which is why diagnostic thresholds are being re-examined rather than carried over unchanged 3. Some supplements can also interfere with certain laboratory methods, so the ordering clinician should know everything you take, prescription or otherwise.
None of this makes testing unreliable. It makes a single number, read in isolation and compared against a figure found online, unreliable. The fix is a well-timed sample, an honest account of what was going on that morning, and a clinician reading the panel as a whole.
No. 'Adrenal fatigue' is not a recognised medical diagnosis, and there is no laboratory test that identifies it.
The idea behind the term is that prolonged stress gradually wears the adrenal glands into a state of partial underperformance that sits somewhere below normal but above diagnosable insufficiency. The adrenal glands do not behave that way. They either make adequate cortisol in response to ACTH or they do not, and the stimulation test exists precisely to distinguish those two states.
What is entirely real is the experience people describe when they use the phrase. Exhaustion that sleep does not repair, poor stress tolerance, brain fog and low drive are genuine symptoms with a long list of recognised causes, including thyroid problems, iron deficiency, sleep apnoea, anaemia, depression, blood sugar dysregulation and, occasionally, true adrenal insufficiency. Attaching an unrecognised label to that cluster tends to stop the search exactly where it should start.
The practical consequence is this. A multi-point saliva panel marketed as an adrenal stress profile is not a substitute for a properly timed morning cortisol with ACTH, and a result from one of those panels will not establish or exclude adrenal insufficiency. If the symptoms are real, the useful move is a structured workup ordered by a clinician who can look beyond the adrenal glands.
Yes, but a narrow and specific one, mostly when the question is whether cortisol is too high rather than too low.
Late-night salivary cortisol works because cortisol should reach its daily low point around bedtime. A value that stays elevated at that hour suggests the normal rhythm has been lost, which is a recognised screening approach for cortisol excess. Saliva also measures the unbound fraction, so it sidesteps the carrier-protein problem that complicates total serum readings.
Twenty-four-hour urinary free cortisol takes the opposite approach, integrating output across a full day and night into one figure. Its weakness is collection, since a missed void or an over-collected jug changes the answer, and kidney function affects the result.
Neither test replaces the morning serum cortisol and ACTH pairing when the suspicion is underactivity. For that question the sequence stays blood-based, with stimulation testing to confirm. The practical rule is that the sample type follows the question, and matching the two is the clinician's job rather than something to sort out at the point of ordering a kit.
Any persistent symptom pattern that fits over- or under-active adrenal function is worth raising with a clinician, and any markedly abnormal result on a panel you already have is worth raising promptly.
Bring it forward sooner in a few situations. Unintended weight loss with nausea and light-headedness on standing, new darkening of skin creases, blood pressure that will not settle despite several medications, a low sodium with a high potassium on routine bloods, or an adrenal nodule mentioned on a scan report all deserve a proper conversation rather than a watch-and-wait.
The emergency case stands apart. Severe weakness, repeated vomiting, confusion or fainting in a person with a known adrenal problem is a medical emergency, and the response is to call 911 rather than to arrange a blood test 7.
For everything else, the value of adrenal testing lies in sequence and context. A morning cortisol with ACTH, read against electrolytes, DHEA-S and your actual symptoms, answers far more than any one marker ordered in isolation. FitScript's membership includes 150+ biomarkers tested per year, with Atlas, the AI health advisor, interpreting them in context, and a licensed provider deciding whether any treatment is appropriate after reviewing the member.
This article is educational and is not medical advice. Discuss your results and any next steps with a clinician or licensed provider who can see your full history.
The usual starting point is a morning serum cortisol, drawn in the first hour or two after waking. Depending on the question, a clinician may add ACTH, DHEA-S, aldosterone and renin, along with sodium, potassium and glucose. If the first results are borderline, an ACTH stimulation test is the step that settles them.
Early, close to your natural waking time, which for most people means around 8 a.m. Cortisol peaks shortly after waking and falls through the day, so a low afternoon value is normal and tells you very little. Night-shift workers have the draw timed to their own waking hour instead of the clock.
Cortisol itself does not usually require fasting, but adrenal markers are often drawn alongside glucose or a lipid panel that does. Follow the instructions your lab or clinician gives for the specific order. Aldosterone and renin testing has extra rules around posture, timing and certain medications, which the ordering clinician will explain in advance.
Rarely. A comfortably high morning cortisol makes underactive adrenal function unlikely, and a very low one makes it much more likely, but values in between leave the question open. That middle zone is exactly why the ACTH stimulation test exists. A clinician decides whether one result is enough or further testing is needed.
Blood is drawn for a baseline cortisol, synthetic ACTH is given by injection in the clinic, and blood is drawn again at set intervals to see how far cortisol rises. It takes roughly an hour of sitting in a clinic. The test is ordered and supervised by a licensed provider, never arranged independently.
Not on its own. Acute illness, pain, a hard workout, a difficult blood draw, pregnancy and the specific assay a lab uses can all raise a total cortisol number. Genuine cortisol excess is assessed with tests that sample a longer window, not with one morning value. Bring any high result to a clinician for context.
No. Adrenal fatigue is not a recognised medical diagnosis and no laboratory test identifies it. The exhaustion and poor stress tolerance people describe are real, and they have a long list of recognised causes worth investigating properly. A structured workup ordered by a clinician is more useful than a saliva panel marketed for this purpose.
Severe weakness, repeated vomiting, confusion or fainting in someone with a known adrenal problem is a medical emergency. Call 911 rather than waiting for an appointment or a lab result. For stable, slower-building symptoms, book a conversation with a clinician who can order the right tests in the right order.