Adrenal Function Tests: Cortisol, ACTH, DHEA-S, Interpretation & Calculator
The adrenal glands are small endocrine organs that produce cortisol, aldosterone and adrenal androgens. Laboratory testing helps evaluate disorders caused by inadequate or excessive adrenal hormone production, including adrenal insufficiency, Cushing syndrome, congenital adrenal hyperplasia and adrenal androgen excess.
This LabDecoded guide explains adrenal function tests, including cortisol, ACTH, DHEA-S, aldosterone and renin, along with dynamic tests such as the ACTH stimulation test, dexamethasone suppression test and 24-hour urinary free cortisol. An interactive calculator is also included to help organize laboratory evaluation.
🧬 What Are Adrenal Function Tests?
Adrenal function tests evaluate the production of hormones from the adrenal cortex and the regulatory pathways controlling them. The three major functional areas are:
🧪 Glucocorticoids
Cortisol is the major glucocorticoid. Testing is used when adrenal insufficiency or cortisol excess is suspected.
đź’§ Mineralocorticoids
Aldosterone regulates sodium and potassium balance and contributes to blood pressure regulation. Renin is interpreted alongside aldosterone.
⚥ Adrenal Androgens
DHEA-S is an adrenal androgen precursor and can help evaluate adrenal androgen excess.
🧪 Cortisol Test
Cortisol is produced by the adrenal cortex under regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Cortisol secretion follows a strong circadian rhythm, normally being highest around the early morning and much lower around midnight.
When is cortisol measured?
- Suspected adrenal insufficiency
- Suspected Addison disease
- Assessment following prolonged glucocorticoid exposure
- Evaluation of suspected Cushing syndrome using appropriate screening tests
- Assessment during selected endocrine investigations
Types of cortisol testing
| Test | Typical clinical use | Important point |
|---|---|---|
| Morning serum cortisol | Initial assessment when adrenal insufficiency is suspected | Interpret with ACTH and clinical context |
| Late-night salivary cortisol | Screening for cortisol excess | Loss of normal nocturnal suppression is important |
| 24-hour urinary free cortisol | Evaluation of endogenous cortisol excess | Requires an appropriately collected 24-hour urine sample |
| Serum cortisol after dexamethasone | Assessment of cortisol suppression | Used in an appropriate dexamethasone suppression protocol |
🧠ACTH Test
Adrenocorticotropic hormone (ACTH) is secreted by the pituitary gland and stimulates the adrenal cortex to produce cortisol.
ACTH is particularly useful when interpreted together with cortisol because the combination can help distinguish primary adrenal disease from secondary or tertiary causes of adrenal insufficiency.
| Cortisol | ACTH | Possible pattern |
|---|---|---|
| Low / inappropriately low | High | Pattern compatible with primary adrenal insufficiency |
| Low / inappropriately low | Low or normal | Pattern compatible with secondary or tertiary adrenal insufficiency |
| High | Low/suppressed | ACTH-independent cortisol excess pattern |
| High | High/inappropriately normal | ACTH-dependent cortisol excess pattern |
🧬 DHEA and DHEA-S Test
DHEA-S (dehydroepiandrosterone sulfate) is produced predominantly by the adrenal cortex and serves as a precursor for sex steroid synthesis.
For routine laboratory assessment of adrenal androgen production, DHEA-S is generally more useful than a random DHEA measurement because DHEA-S has a longer half-life and is present at more stable circulating concentrations.
When is DHEA-S measured?
- Hirsutism or unexplained androgen excess
- Rapidly progressive virilization
- Suspected adrenal androgen excess
- Evaluation of suspected adrenal androgen-producing tumors
- Selected cases of congenital adrenal hyperplasia
- Evaluation of adrenal disorders in children or adolescents when clinically appropriate
đź’§ Aldosterone and Renin Testing
Aldosterone is the principal mineralocorticoid produced by the adrenal cortex. It promotes sodium retention and potassium excretion and is an important component of blood pressure and volume regulation.
The aldosterone-to-renin ratio (ARR) is commonly used when screening for primary aldosteronism.
When may aldosterone and renin be requested?
- Hypertension with unexplained hypokalemia
- Resistant hypertension
- Selected patients with early-onset or severe hypertension
- Other clinical situations where primary aldosteronism is suspected
🔬 Dynamic Tests of Adrenal Function
Some adrenal disorders cannot be diagnosed reliably from a single hormone measurement. Dynamic endocrine tests challenge or suppress a hormonal pathway and measure the physiological response.
1. ACTH Stimulation Test
The ACTH stimulation test is commonly used to assess adrenal cortisol reserve when adrenal insufficiency is suspected. Synthetic ACTH is administered and cortisol is measured at specified intervals according to the protocol.
Interpretation depends on the ACTH preparation, sampling schedule and cortisol assay. Historical cortisol cutoffs should not automatically be transferred between different assays.
2. Overnight Dexamethasone Suppression Test
Dexamethasone suppresses ACTH in normal physiology. Failure of cortisol to suppress appropriately can support the evaluation of endogenous cortisol excess.
3. 24-Hour Urinary Free Cortisol
Urinary free cortisol estimates the amount of biologically active cortisol excreted in urine over a complete 24-hour period. Collection errors, kidney function and certain medications can affect interpretation.
4. Late-Night Salivary Cortisol
Because normal cortisol production falls substantially at night, an inappropriately elevated late-night salivary cortisol can be useful when evaluating suspected Cushing syndrome.
đź“Š How to Interpret Cortisol and ACTH Together
| Biochemical Pattern | Possible Interpretation |
|---|---|
| Low cortisol + high ACTH | Suggests primary adrenal insufficiency pattern |
| Low cortisol + low/inappropriately normal ACTH | Suggests central adrenal insufficiency pattern |
| High cortisol + suppressed ACTH | Suggests ACTH-independent cortisol excess |
| High cortisol + elevated/inappropriately normal ACTH | Suggests ACTH-dependent cortisol excess |
The biochemical pattern should be integrated with symptoms, medication history, imaging and appropriate dynamic testing.
đź“‹ Adrenal Hormone Reference Ranges
There is no single universal "normal range" for adrenal hormones. Reference intervals depend on the assay, laboratory, age, sex, sampling time and clinical circumstances.
| Test | Why a fixed range can be misleading | Interpretation |
|---|---|---|
| Serum cortisol | Strong circadian variation and assay differences | Consider sampling time and clinical question |
| ACTH | Diurnal variation and specimen handling requirements | Interpret with cortisol |
| DHEA-S | Strong age and sex dependence | Use laboratory-specific age/sex interval |
| Aldosterone | Posture, sodium intake and medications influence results | Interpret with renin and clinical context |
| Renin | Highly affected by posture, sodium and medications | Interpret with aldosterone |
⚕️ Common Adrenal Disorders
Addison Disease
Primary adrenal insufficiency caused by inadequate adrenal hormone production. Autoimmune adrenal destruction is an important cause in many populations.
Cushing Syndrome
A state of chronic cortisol excess. Causes include exogenous glucocorticoid exposure and endogenous ACTH-dependent or ACTH-independent disorders.
Congenital Adrenal Hyperplasia
A group of inherited steroidogenic enzyme disorders. 21-hydroxylase deficiency is the most common form.
Primary Aldosteronism
Excess aldosterone production causing sodium retention and inappropriate renin suppression, often presenting with hypertension.
Adrenal Tumors
Some adrenal tumors are hormonally silent while others produce cortisol, aldosterone, androgens or catecholamines.
Central Adrenal Insufficiency
Reduced ACTH drive from pituitary or hypothalamic disease can result in inadequate cortisol production.
🧪 Adrenal Function Test Interpretation & Priority Calculator
Adrenal Laboratory Evaluation Calculator
Educational screening tool for organizing adrenal laboratory evaluation. It does not diagnose an adrenal disorder.
Adrenal Laboratory Evaluation Summary
Potential laboratory areas
This is an educational laboratory-planning calculator, not a validated diagnostic score. A high score does not establish adrenal disease, and a low score does not exclude it.
⚠️ Common Laboratory Pitfalls in Adrenal Testing
1. Ignoring collection time
Cortisol and ACTH have pronounced circadian variation. A cortisol result without collection time can therefore be difficult to interpret.
2. Using one cortisol cutoff for every assay
Cortisol assays differ analytically. Cutoffs used for dynamic testing should be appropriate for the assay and protocol.
3. Treating DHEA-S as a universal adrenal tumor marker
An elevated DHEA-S can occur for several reasons. The magnitude of elevation, age, clinical presentation and other androgen measurements all matter.
4. Ignoring medications
Glucocorticoids, hormonal medications and several other drugs can influence endocrine testing. Medication history should be reviewed before interpretation.
5. Misinterpreting aldosterone-renin ratio
ARR is particularly vulnerable to pre-analytical and pharmacological factors. Potassium, sodium intake, posture and antihypertensive medications can all influence the result.
6. Using random cortisol to screen for Cushing syndrome
A random cortisol measurement does not reliably assess the loss of normal circadian rhythm associated with Cushing syndrome. Appropriate first-line screening tests should be selected according to clinical guidelines.
🧪 Adrenal Testing in Laboratory Practice
Adrenal hormones present several unique challenges for clinical laboratories. Sample collection, transport, timing and assay selection can have a major effect on interpretation.
Pre-analytical
Document collection time, relevant medications and clinical circumstances. ACTH requires appropriate specimen handling because it is relatively unstable.
Analytical
Use validated methods and assay-specific reference intervals. Dynamic-test interpretation should use cutoffs appropriate to the assay.
Post-analytical
Reports should provide units, reference intervals and relevant interpretive comments where appropriate.
đź©ş Adrenal Insufficiency vs Cushing Syndrome
| Feature | Adrenal Insufficiency | Cortisol Excess |
|---|---|---|
| Cortisol | Inappropriately low | Inappropriately elevated or inadequately suppressed |
| ACTH | Helps distinguish primary from central disease | Helps distinguish ACTH-dependent from ACTH-independent disease |
| Potassium | May be elevated in primary adrenal insufficiency | May be reduced in selected ACTH-mediated states |
| Blood pressure | May be low | Often elevated |
| Dynamic testing | ACTH stimulation commonly used | Dexamethasone suppression, urinary free cortisol or late-night salivary cortisol depending on presentation |
❓ Frequently Asked Questions About Adrenal Function Tests
1. What are the main adrenal function tests?
The main tests depend on the suspected disorder and include cortisol, ACTH, DHEA-S, aldosterone, renin and selected dynamic endocrine tests.
2. What is the best time for a cortisol blood test?
When evaluating suspected adrenal insufficiency, an early morning cortisol is commonly used because cortisol is normally near its daily peak at that time. The exact collection time should be documented.
3. Can stress increase cortisol?
Yes. Physical illness, psychological stress and other physiological factors can influence cortisol concentrations. Interpretation therefore requires clinical context.
4. What is the difference between DHEA and DHEA-S?
DHEA-S is the sulfated form of DHEA and has a longer circulating half-life and more stable concentration. DHEA-S is therefore commonly used for laboratory assessment of adrenal androgen production.
5. Is DHEA-S a test for adrenal tumors?
DHEA-S can contribute to the evaluation of adrenal androgen excess, but an elevated result does not by itself diagnose an adrenal tumor.
6. What does low cortisol with high ACTH suggest?
This biochemical pattern is compatible with primary adrenal insufficiency, but confirmatory assessment is usually required.
7. What does low cortisol with low ACTH suggest?
This pattern can occur with central adrenal insufficiency caused by inadequate pituitary or hypothalamic ACTH drive.
8. What does high cortisol with low ACTH suggest?
This can indicate an ACTH-independent cortisol excess pattern, such as cortisol production arising from the adrenal gland. Further testing is required.
9. Can a single cortisol test diagnose Addison disease?
Usually not. Morning cortisol and ACTH can provide important initial information, but dynamic testing and other investigations may be needed.
10. Can a random cortisol test diagnose Cushing syndrome?
No. Random serum cortisol is not generally an appropriate stand-alone screening test for Cushing syndrome. Specific screening approaches are used instead.
11. What test evaluates aldosterone excess?
Aldosterone and renin are commonly measured together, with the aldosterone-to-renin ratio used as a screening tool for primary aldosteronism in appropriate patients.
12. Can steroid medicines affect adrenal testing?
Yes. Glucocorticoid exposure can suppress the HPA axis and can also interfere with interpretation depending on the medication and assay. The medication history is essential.
đź”— Related LabDecoded Topics
- Understanding Thyroid Function Tests
- Serum Ferritin and Iron Studies
- Uric Acid: Hyperuricemia and Gout
✅ Key Takeaways
1. Cortisol Is Time Dependent
Collection time is essential because cortisol follows a strong circadian rhythm.
2. ACTH Adds Context
Cortisol and ACTH together help distinguish primary from central adrenal disorders.
3. DHEA-S Is Usually Preferred
DHEA-S is more stable than DHEA and is commonly used for adrenal androgen assessment.
4. Dynamic Tests Matter
ACTH stimulation and suppression tests may be necessary because one hormone result may not answer the clinical question.
5. ARR Requires Care
Aldosterone-renin ratio is affected by medications, potassium, sodium intake and posture.
6. Reference Ranges Are Laboratory Specific
Age, sex, assay methodology and sampling conditions must be considered.
🔬 Laboratory Medicine Perspective
Adrenal testing is a good example of why endocrine laboratory results should not be interpreted in isolation. The same cortisol concentration can have different clinical implications depending on whether it was collected at 8 AM, late evening, after dexamethasone, during acute illness or following glucocorticoid treatment.
For this reason, an effective adrenal testing strategy starts with the clinical question and then selects the appropriate biochemical test. Accurate specimen collection, validated analytical methods and assay-specific interpretation are equally important.
SEO topics: adrenal function tests, adrenal function test, cortisol test, ACTH test, DHEA-S test, DHEAS test, adrenal hormone tests, adrenal insufficiency test, Addison disease test, Cushing syndrome test, cortisol blood test, morning cortisol, ACTH cortisol interpretation, adrenal gland tests, aldosterone renin test, aldosterone renin ratio, ACTH stimulation test, dexamethasone suppression test, 24 hour urinary free cortisol, late night salivary cortisol, adrenal androgen testing, adrenal function calculator
0 Comments