Understanding Your Adrenal Hormone Tests

Section Editors: Christopher McCudden Ph.D., DABCC, FADLM, FCACB and Kamran Mirza MD PhD
June 11, 2026

Adrenal hormone tests are a group of blood, urine, and saliva tests used to evaluate how well the adrenal glands are working. The adrenal glands are two small glands sitting on top of the kidneys. Despite their size, they produce some of the most important hormones in the body — including cortisol, which regulates the stress response and helps regulate blood sugar and blood pressure; aldosterone, which regulates salt and water balance; and small amounts of sex hormones. When adrenal hormone production is too high or too low, it can affect almost every organ system, often in ways that are easy to mistake for other conditions.

This article explains what each adrenal hormone test measures, why the tests are ordered, how they are interpreted together, and what may need to happen next. You may find this article helpful if your blood test report includes cortisol or ACTH results, if your doctor has mentioned Addison’s disease, Cushing’s syndrome, or adrenal insufficiency, or if an adrenal nodule has been found on imaging and your doctor has ordered hormone tests to evaluate it.

The reference range that applies to your result is the one printed on your laboratory report, not the typical ranges shown here. Reference ranges for adrenal hormones depend heavily on the time of day the sample was drawn, the type of sample (blood, urine, or saliva), whether any medications were taken, recent stress, and the laboratory. Always compare your result to the reference range printed on your own report, and discuss any abnormal result with your doctor.

How the adrenal glands work

The adrenal glands are two small glands located on top of the kidneys that produce some of the body’s most important hormones. Understanding how these glands work is the key to making sense of adrenal hormone test results.

Each adrenal gland has two parts that produce different hormones:

The adrenal cortex — the outer layer of the gland. It produces three groups of hormones: glucocorticoids (the main one is cortisol), mineralocorticoids (the main one is aldosterone), and small amounts of adrenal androgens (such as DHEA and DHEA-S).
The adrenal medulla — the inner core of the gland. It produces catecholamines, including adrenaline (epinephrine) and noradrenaline (norepinephrine), which are released during stress.

Cortisol production is controlled by a feedback loop similar to that controlling the thyroid. The hypothalamus (an area at the base of the brain) releases corticotropin-releasing hormone (CRH), which signals the pituitary gland to release adrenocorticotropic hormone (ACTH). ACTH travels through the bloodstream to the adrenal cortex, signaling it to produce cortisol. When cortisol levels in the blood are high enough, the brain reduces its output of CRH and ACTH, completing the loop. This system is called the hypothalamic-pituitary-adrenal axis, often shortened to the HPA axis.

Cortisol production follows a strong daily rhythm. Levels are highest in the early morning (around 6 to 8 a.m.) and lowest around midnight. This rhythm is the reason most cortisol tests are done at specific times of day — a “normal” cortisol level at 8 a.m. and a “normal” cortisol level at midnight mean very different things.

Aldosterone is regulated by a separate system that responds to blood pressure and salt balance. When blood pressure drops or sodium levels fall, the kidneys release an enzyme called renin, which triggers a chain of events leading to the release of aldosterone. Aldosterone then tells the kidneys to hold on to sodium and water, raising blood pressure back toward normal.

Why are adrenal hormone tests done?

Adrenal hormone tests are blood, urine, and saliva tests used to evaluate how well the adrenal glands — the small glands sitting on top of the kidneys — are working. They measure cortisol (which regulates the stress response, blood sugar, and blood pressure), aldosterone (which regulates salt and water balance), the pituitary hormone ACTH that controls cortisol production, and several related hormones. Tests are ordered for many reasons, including:

To investigate symptoms of high cortisol. Unexplained weight gain (especially around the trunk and face), high blood pressure, easy bruising, purple stretch marks, muscle weakness, mood changes, and new diabetes can all raise concern for Cushing’s syndrome.
To investigate symptoms of low cortisol. Profound fatigue, weight loss, low blood pressure, salt cravings, darkening of the skin, nausea, and unexplained low blood sodium or high blood potassium can suggest adrenal insufficiency.
To investigate difficult-to-control high blood pressure. Primary aldosteronism (also called Conn’s syndrome) is increasingly recognized as a common cause of hypertension that does not respond to standard medications. Aldosterone and renin levels are the screening tests.
To evaluate an adrenal nodule found on imaging. Adrenal nodules are common and often discovered by chance on CT or MRI performed for an unrelated reason. Even when the nodule looks benign, hormone testing is used to determine whether it is producing excess hormone.
To investigate suspected pheochromocytoma. Episodes of severe headache, sweating, and a racing heart, particularly together with high blood pressure, can suggest a tumor of the adrenal medulla called a pheochromocytoma.
To investigate fatigue and other nonspecific symptoms. Adrenal hormone tests are sometimes ordered as part of a broader workup when symptoms do not have an obvious cause.
To monitor known adrenal disease. Patients with diagnosed adrenal insufficiency, Cushing’s syndrome, or congenital adrenal hyperplasia have adrenal hormone tests repeated to follow their condition and adjust treatment.
To check adrenal reserve after long-term steroid use. Long-term use of glucocorticoid medications (such as prednisone) can suppress the adrenal glands. When these medications are stopped, hormone testing may be used to confirm that the adrenal glands have recovered.

How are the tests performed?

Adrenal hormone tests evaluate how well the adrenal glands (the small glands above the kidneys) and the hormones that control them are functioning. The tests can use blood, urine, or saliva samples. The type of sample depends on what is being measured:

Blood samples are used for cortisol, ACTH, aldosterone, renin, DHEA-S, and plasma metanephrines. Most are drawn from a vein in the arm. Cortisol is usually measured first thing in the morning. If a midnight cortisol is needed, it is typically drawn in a hospital setting because the patient must be at rest and the timing must be precise.
Urine samples are used for 24-hour urinary free cortisol and for urinary metanephrines. A 24-hour urine collection means saving all urine produced over a full day in a special container provided by the laboratory.
Saliva samples are used for late-night salivary cortisol. The patient collects a small saliva sample at home between 11 p.m. and midnight on two separate nights, using a laboratory-provided kit.

Several adrenal tests are dynamic tests, in which a hormone is measured before and after a medication is given. The medication either stimulates or suppresses normal adrenal activity, and the way the adrenal glands respond gives more information than a single resting measurement could. Dynamic tests include the dexamethasone suppression test (which screens for Cushing’s syndrome) and the ACTH stimulation test (which assesses adrenal reserve). These tests have specific protocols that your doctor or the laboratory will explain in detail.

Many medications affect adrenal hormone results, including glucocorticoid medications (such as prednisone, hydrocortisone, and dexamethasone), oral contraceptives, certain blood pressure medications (especially those used for hypertension), opioids, and some antifungal drugs. Your doctor will tell you whether to hold or continue any medications before testing. Recent stress, acute illness, vigorous exercise, and disrupted sleep can also affect results, so testing is generally best done when you are otherwise well and rested.

The adrenal hormone tests

The adrenal glands sit atop the kidneys and produce three main groups of hormones: glucocorticoids (mainly cortisol, which regulates the stress response, blood sugar, and blood pressure), mineralocorticoids (mainly aldosterone, which regulates salt and water balance), and small amounts of sex hormones. The adrenal medulla, the inner core of each gland, produces catecholamines (such as adrenaline). Cortisol production is controlled by the pituitary gland, which releases adrenocorticotropic hormone (ACTH). Aldosterone production is controlled separately, mainly by the kidney enzyme renin. The tests described below measure these hormones — sometimes at rest, and sometimes after a medication is given to stimulate or suppress normal adrenal activity.

Cortisol

Cortisol is the most important adrenal hormone for routine clinical testing. It helps the body respond to physical and emotional stress, regulates blood sugar and blood pressure, and influences immune function. Because cortisol levels change so much throughout the day, the result is meaningful only when interpreted together with the time the sample was drawn.

Several different cortisol measurements are used in different situations:

Morning serum cortisol — drawn between 6 and 8 a.m., when cortisol is normally at its highest. A typical reference range is approximately 5 to 25 micrograms per decilitre (mcg/dL). A low morning cortisol suggests possible adrenal insufficiency and usually requires further testing to confirm.
Late-night serum or salivary cortisol — drawn around midnight, when cortisol is normally at its lowest. A high midnight cortisol is one of the most sensitive findings for Cushing’s syndrome, in which the normal daily rhythm is lost.
Random cortisol — drawn without regard to time of day. Most useful in critically ill patients, where a very low value strongly suggests adrenal insufficiency.

Most cortisol in the blood is bound to a carrier protein called cortisol-binding globulin (CBG), with only a small free fraction biologically active. Conditions that change CBG levels (such as pregnancy, oral contraceptives, or severe liver disease) can shift total cortisol up or down without any true change in adrenal function. Salivary cortisol measures the free, active fraction and is not affected by changes in CBG.

Causes of high cortisol:

Cushing’s syndrome from any cause, including a pituitary tumor producing excess ACTH (Cushing’s disease), an adrenal tumor producing cortisol directly, or a tumor elsewhere in the body producing ACTH (ectopic ACTH syndrome)
Exogenous Cushing’s syndrome from long-term use of glucocorticoid medications such as prednisone (the most common cause overall)
Severe acute or chronic stress, depression, alcohol use disorder, and poorly controlled diabetes (sometimes called “pseudo-Cushing’s”)
Pregnancy (cortisol rises during pregnancy as CBG increases)

Causes of low cortisol:

Primary adrenal insufficiency (Addison’s disease), in which the adrenal glands themselves are damaged or destroyed
Secondary adrenal insufficiency, in which the pituitary fails to produce enough ACTH
Long-term suppression from previous glucocorticoid medication use
Acute critical illness in some patients

24-hour urinary free cortisol

This test measures the total amount of unbound cortisol the kidneys excrete in urine over a 24-hour period. Because it averages cortisol production across the whole day, it smooths out the normal daily rhythm and reflects total cortisol exposure. A clearly elevated result is one of the most useful screening tests for Cushing’s syndrome.

The accuracy of this test depends entirely on collecting all the urine produced over the 24-hour period. Missing even one sample can make the result misleading. Two or three separate collections are often performed because the results can vary from day to day.

Adrenocorticotropic hormone (ACTH)

ACTH is the pituitary hormone that signals the adrenal cortex to produce cortisol. Measuring ACTH alongside cortisol is essential when cortisol levels are abnormal, because the two results together help identify the source of the problem.

High cortisol with high ACTH — suggests the problem is producing too much ACTH, which is overstimulating the adrenal glands. The source may be a pituitary tumor (Cushing’s disease) or a tumor elsewhere in the body that produces ACTH (ectopic ACTH syndrome).
High cortisol with low ACTH — suggests the adrenal gland itself is producing too much cortisol independently of the pituitary, often from an adrenal tumor. The pituitary appropriately suppresses ACTH in response to high cortisol.
Low cortisol with high ACTH — suggests primary adrenal insufficiency. The pituitary is producing extra ACTH in an effort to stimulate the failing adrenal glands.
Low cortisol with low or inappropriately normal ACTH — suggests secondary adrenal insufficiency. The pituitary is not producing enough ACTH, so the adrenal glands receive no signal to make cortisol.

ACTH is a sensitive and unstable hormone in blood samples, so the laboratory has specific requirements for how samples are collected, transported, and processed.

Aldosterone

Aldosterone is the principal mineralocorticoid produced by the adrenal cortex. It tells the kidneys to retain sodium and excrete potassium, which helps maintain blood pressure and salt balance. Aldosterone is regulated by the renin-angiotensin system rather than by ACTH, so its production is largely independent of cortisol.

Aldosterone is most often measured when investigating high blood pressure that is not well controlled with standard medications, particularly when the patient also has a low blood potassium level. Like cortisol, aldosterone follows a daily rhythm, and morning sampling is preferred.

Causes of high aldosterone:

Primary aldosteronism (Conn’s syndrome) from an aldosterone-producing adrenal nodule or from generalized overproduction by both adrenal glands
Secondary aldosteronism, in which the kidneys release excess renin in response to reduced blood flow (as in kidney artery narrowing, heart failure, or cirrhosis with fluid retention)
Diuretic medications, particularly those that lower blood potassium

Causes of low aldosterone:

Primary adrenal insufficiency (Addison’s disease)
Certain inherited conditions affecting hormone production
Medications that block the renin-angiotensin system, such as ACE inhibitors and angiotensin receptor blockers

Plasma renin activity (PRA) or direct renin concentration

Renin is the kidney enzyme that triggers aldosterone production. Measuring it alongside aldosterone is essential when investigating primary aldosteronism. The two tests measure essentially the same thing in different ways — plasma renin activity measures how much new angiotensin the renin can produce, while direct renin concentration measures the amount of renin protein in the blood. Most laboratories now use direct renin concentration because it is more reproducible.

The most useful single number for screening primary aldosteronism is the aldosterone-renin ratio (ARR), calculated by dividing the aldosterone level by the renin level. A high ARR suggests that aldosterone production is inappropriately high relative to renin and is the standard screening test for primary aldosteronism. A clearly elevated ARR usually prompts a confirmatory test (such as a saline infusion test) before making the diagnosis.

Many blood pressure medications affect renin and aldosterone levels and can interfere with the interpretation of the ARR. Your doctor may ask you to switch to medications that have less effect on these hormones (such as certain calcium channel blockers and alpha-blockers) for several weeks before the test.

Dexamethasone suppression tests

The dexamethasone suppression test is used to investigate suspected Cushing’s syndrome. Dexamethasone is a synthetic glucocorticoid medication that, when given to a person without Cushing’s syndrome, suppresses the pituitary’s release of ACTH and the adrenal glands’ release of cortisol. People with Cushing’s syndrome do not show this normal suppression.

Two main versions are used:

Low-dose (overnight) dexamethasone suppression test — the patient takes 1 milligram of dexamethasone at 11 p.m., and serum cortisol is measured at 8 a.m. the next morning. A clearly suppressed cortisol level is reassuring; a result above a defined threshold (typically 1.8 mcg/dL) suggests possible Cushing’s syndrome and prompts further evaluation.
High-dose dexamethasone suppression test — a larger dose is given, typically over 48 hours. This is used in cases of confirmed Cushing’s syndrome to help distinguish a pituitary cause (which often partially suppresses) from an adrenal or ectopic cause (which usually does not suppress).

ACTH stimulation test (cosyntropin test)

This test is used to investigate suspected adrenal insufficiency. A synthetic form of ACTH (called cosyntropin or tetracosactide) is injected, and serum cortisol is measured before the injection and 30 to 60 minutes afterward. In a person with healthy adrenal glands, cortisol rises sharply in response. In primary adrenal insufficiency, the adrenal glands cannot respond, and cortisol remains low. In long-standing secondary adrenal insufficiency, the adrenal glands have shrunk from prolonged lack of ACTH stimulation and respond poorly, even though the gland itself is intact.

A cortisol level above approximately 18 to 20 mcg/dL after stimulation is generally considered a normal response. The exact cutoff depends on the assay used by the laboratory.

Plasma metanephrines (and urinary metanephrines)

Metanephrines are the breakdown products of adrenaline and noradrenaline. They are more stable in the blood than the parent hormones, so measuring them is a more reliable way to identify excess catecholamine production. Plasma free metanephrines or 24-hour urinary fractionated metanephrines are the standard tests when a pheochromocytoma or a related tumor called a paraganglioma is suspected.

For accurate results, the patient should be in a supine (lying down) position for at least 30 minutes before the blood draw. Many foods and medications can falsely elevate metanephrine levels, and your doctor will give specific instructions about what to avoid before the test.

A clearly elevated result usually prompts imaging of the adrenal glands and sometimes other parts of the body to look for a tumor. Mildly elevated results are often re-tested and may require further investigation to distinguish a true tumor from a false-positive result.

DHEA-S

DHEA-S (dehydroepiandrosterone sulfate) is the main androgen produced by the adrenal cortex. It is often included in evaluations of androgen excess (such as polycystic ovary syndrome and other causes of hirsutism in women) and in evaluations of adrenal tumors. DHEA-S is also covered in our article on Understanding your reproductive hormone panel. A markedly elevated DHEA-S in a woman with rapid onset of male-pattern hair growth or other signs of androgen excess raises concern for an adrenal tumor producing androgens.

How the tests work together: common patterns

Adrenal hormone tests measure cortisol (controlled by the pituitary hormone ACTH), aldosterone (controlled by the kidney enzyme renin), and the breakdown products of adrenaline (called metanephrines). These hormones together describe how the adrenal glands are functioning. The results are usually most meaningful when interpreted as a pattern across several tests rather than as a single number. Some of the most common patterns are described below.

Cushing’s syndrome

Cushing’s syndrome refers to the constellation of findings caused by long-term exposure to excessive cortisol, regardless of the cause. The most common cause overall is the use of glucocorticoid medications such as prednisone, called exogenous or iatrogenic Cushing’s. When cortisol excess comes from the body’s own production, it is called endogenous Cushing’s syndrome.

Typical findings in endogenous Cushing’s syndrome include an elevated 24-hour urinary free cortisol, an elevated late-night salivary cortisol, and failure of cortisol to suppress on the low-dose dexamethasone suppression test. Two or three of these screening tests are usually performed because none of them alone is perfect. Once Cushing’s syndrome is confirmed, the next step is to measure ACTH:

ACTH-dependent Cushing’s syndrome — ACTH is elevated. The most common cause is a pituitary tumor producing ACTH, called Cushing’s disease. Less commonly, a tumor elsewhere in the body (often in the lung or pancreas) produces ACTH, called ectopic ACTH syndrome.
ACTH-independent Cushing’s syndrome — ACTH is low or suppressed. The source is the adrenal gland itself, usually a cortisol-producing adrenal cortical adenoma, less commonly a cortisol-producing adrenal cortical carcinoma, or rarely a process affecting both adrenal glands.

Primary adrenal insufficiency (Addison’s disease)

In primary adrenal insufficiency, the adrenal glands themselves are damaged or destroyed. The pattern is low cortisol (often very low), high ACTH (the pituitary is trying hard to stimulate the failing adrenals), low or low-normal aldosterone, and failure to respond to the ACTH stimulation test. Blood sodium is often low and blood potassium is often high. The most common cause in countries with adequate medical care is autoimmune destruction of the adrenal cortex. Other causes include infection (such as tuberculosis), bleeding into the adrenal glands, and metastatic cancer affecting both adrenals.

Secondary (central) adrenal insufficiency

When the pituitary fails to produce enough ACTH, the adrenal glands receive no signal to make cortisol and gradually shrink. The pattern is low cortisol with low or inappropriately normal ACTH. Aldosterone is usually preserved because it is regulated separately. The ACTH stimulation test typically shows a blunted cortisol response because the adrenal glands have lost their normal mass. The most common cause is long-term suppression from previous glucocorticoid medication use. Less common causes include pituitary tumors, pituitary surgery or radiation, and disorders affecting the hypothalamus.

Primary aldosteronism (Conn’s syndrome)

Primary aldosteronism is now recognized as one of the most common identifiable causes of high blood pressure. The pattern is an elevated aldosterone, a suppressed renin, and therefore an elevated aldosterone-renin ratio. Blood potassium is often low. The condition is usually caused by an aldosterone-producing adrenal nodule or by generalized overproduction from both adrenal glands. Confirmation typically requires a saline infusion test, an oral salt loading test, or another dynamic test, after which imaging and sometimes a specialized procedure called adrenal venous sampling are used to identify the source.

Pheochromocytoma and paraganglioma

These are tumors that produce excess catecholamines and the patterns they cause can be dramatic. Findings include clearly elevated plasma free metanephrines or 24-hour urinary fractionated metanephrines, often accompanied by high blood pressure (frequently episodic), headaches, sweating, and a racing heart. Once biochemically confirmed, imaging is performed to locate the tumor. A significant proportion of these tumors are associated with inherited syndromes, so genetic testing is often offered.

Adrenal nodule found on imaging (incidentaloma)

When an adrenal nodule is discovered by chance on imaging done for an unrelated reason, the standard workup includes hormone testing to determine whether the nodule is producing excess hormone. The usual tests are a low-dose dexamethasone suppression test (to assess for cortisol overproduction), plasma free metanephrines (to assess for pheochromocytoma), and, if the patient has hypertension or low potassium, an aldosterone-to-renin ratio (to assess for primary aldosteronism). Most adrenal nodules are not hormone-producing and not cancerous, but the small number that are need to be identified.

What happens after adrenal hormone testing?

Adrenal hormone testing — including cortisol, ACTH, aldosterone, renin, and metanephrines — is used to determine whether the adrenal glands are producing too much, too little, or the right amount of hormone, and to identify the cause when the production is abnormal. The next steps depend on the results and the clinical situation. Possibilities include:

Repeat the test. Many adrenal abnormalities are confirmed by repeating the test, particularly when the initial result is borderline or could have been affected by stress, medications, or timing. Cortisol and metanephrine results, in particular, are often repeated.
Add a confirmatory test. Screening tests for Cushing’s syndrome and primary aldosteronism are not specific enough to make a diagnosis on their own. Confirmatory testing typically follows a positive screen — for example, a saline infusion test for primary aldosteronism, or a high-dose dexamethasone suppression test or inferior petrosal sinus sampling for Cushing’s disease.
Imaging. CT or MRI of the adrenal glands is the standard imaging test when an adrenal cause of hormone excess is suspected or when the diagnosis is already established and the source of the problem is being localized. Pituitary MRI is performed when a pituitary cause is suspected.
Referral to an endocrinologist. Most complex adrenal hormone problems are referred to an endocrinologist (a hormone specialist) who manages further testing, treatment, and long-term follow-up.
Treatment based on the cause. Treatment varies widely. Adrenal insufficiency is treated with daily hydrocortisone or another glucocorticoid medication, and in primary adrenal insufficiency, a mineralocorticoid (fludrocortisone) is added. Hormone-producing adrenal nodules are usually treated with surgery to remove the affected adrenal gland. Cushing’s disease from a pituitary tumor is typically treated with pituitary surgery, sometimes followed by radiation or medical therapy. Primary aldosteronism is treated with surgery for one-sided disease and with medications that block aldosterone (such as spironolactone or eplerenone) for generalized disease. Pheochromocytomas are treated with surgery after careful medical preparation.
Genetic counseling. Several adrenal conditions, particularly pheochromocytoma, paraganglioma, and some forms of congenital adrenal hyperplasia, have inherited components that affect family members. Genetic counseling and testing are often recommended.
Monitoring over time. Patients with known adrenal disease, on treatment, or with adrenal nodules that have not been removed have hormone testing repeated at intervals to track changes and adjust management.

An important point to keep in mind is that adrenal hormone tests are highly sensitive to timing, stress, sleep, medications, and sample collection. A single abnormal result is rarely enough to make a diagnosis, and a single normal result is not always reassuring. Your clinician will interpret the pattern of results in the context of your symptoms and other findings.

Questions to ask your doctor

Why were these tests ordered, and what specific condition is being investigated?
Which of my results were outside the reference range?
Did the timing of the blood draw, urine collection, or saliva collection affect any of the results?
Could any of my medications be affecting the results?
If a result was abnormal, should it be confirmed with a repeat test or a different test?
Do I need a dynamic test such as a dexamethasone suppression test or an ACTH stimulation test?
If Cushing’s syndrome or adrenal insufficiency is suspected, what are the next steps to confirm or rule out the diagnosis?
If my blood pressure is hard to control, should primary aldosteronism be investigated?
If an adrenal nodule was found on imaging, do my hormone test results suggest it is producing hormones?
Should I have imaging of the adrenal glands or the pituitary gland?
Should I be referred to an endocrinologist?
Should genetic testing be considered?
When should the tests be repeated?