Cortisol and dehydroepiandrosterone (DHEA) are the two primary adrenal steroids that clinicians use to assess the functional status of the hypothalamic‑pituitary‑adrenal (HPA) axis. While both hormones fluctuate throughout the day and are influenced by a myriad of physiological and pathological factors, the decision to order a test—and the way the test is performed—can be the difference between a clear diagnostic picture and a misleading result. This article provides a practical, evidence‑based roadmap for clinicians who need to determine when to test cortisol and DHEA as part of routine screening, how to choose the appropriate assay, and what steps to take after the results are in hand.
Clinical Scenarios That Prompt Testing
| Situation | Rationale for Testing | Preferred Initial Test |
|---|---|---|
| Unexplained weight change (gain or loss) | Cortisol excess can promote central adiposity; deficiency may contribute to weight loss and muscle wasting. | Morning serum cortisol |
| Persistent fatigue or malaise | Both hyper‑ and hypocortisolism can manifest as non‑specific fatigue; DHEA decline is linked to reduced vitality. | Morning serum cortisol + DHEA‑S |
| Hypertension refractory to standard therapy | Cushing‑type hypercortisolism is a treatable cause of resistant hypertension. | 24‑hour urinary free cortisol (UFC) or late‑night salivary cortisol |
| Electrolyte abnormalities (hypokalemia, metabolic alkalosis) | Suggests mineralocorticoid excess often accompanying cortisol overproduction. | Midnight salivary cortisol or UFC |
| Adrenal incidentaloma discovered on imaging | Need to exclude autonomous hormone production. | Overnight dexamethasone suppression test (DST) plus baseline cortisol |
| Symptoms of androgen excess (hirsutism, acne) in women | Elevated DHEA‑S can be a source of excess androgens. | Serum DHEA‑S |
| Evaluation of pituitary or adrenal disorders (e.g., suspected Addison’s disease) | Low cortisol and low DHEA‑S are hallmarks of primary adrenal insufficiency. | Morning cortisol + ACTH stimulation test |
| Pre‑operative assessment for major surgery | Identifying adrenal insufficiency reduces peri‑operative risk. | Morning cortisol; consider ACTH stimulation if borderline |
| Monitoring known adrenal disease (Cushing’s, Addison’s) | Serial measurements gauge disease activity and treatment response. | Same assay used for baseline (UFC, serum cortisol, or salivary cortisol) for consistency |
| Screening in high‑risk groups (e.g., patients on chronic glucocorticoids, those with pituitary tumors) | Early detection of HPA axis suppression or hyperactivity. | Morning cortisol; consider dynamic testing if clinically indicated |
Choosing Between Static and Dynamic Tests
- Static (single‑point) measurements
- Serum cortisol (usually drawn at 8 am) provides a snapshot of adrenal output.
- Serum DHEA‑S is relatively stable throughout the day, making a single measurement reliable.
- Urinary free cortisol (UFC) reflects integrated cortisol secretion over 24 hours, smoothing out diurnal peaks and troughs.
- Salivary cortisol (especially late‑night) captures the nadir of the diurnal rhythm and is useful for detecting loss of circadian variation.
- Dynamic (stimulus‑response) tests
- ACTH (cosyntropin) stimulation test evaluates adrenal reserve; a rise in cortisol ≥ 18–20 µg/dL after 30–60 minutes is considered normal.
- Low‑dose dexamethasone suppression test (DST) assesses feedback inhibition; failure to suppress cortisol < 1.8 µg/dL after overnight 1 mg dexamethasone suggests autonomous secretion.
- CRH stimulation test is rarely needed in routine screening but can help differentiate pituitary from ectopic ACTH sources when the diagnosis is already suspected.
Practical tip: Begin with a static test that matches the clinical suspicion. Reserve dynamic testing for equivocal results or when a definitive functional assessment is required.
Timing and Sample Collection: The “When” of the Test
| Test | Optimal Timing | Reason |
|---|---|---|
| Morning serum cortisol | 7:00–9:00 am (within 30 minutes of waking) | Captures the peak of the diurnal curve; minimizes variability. |
| Late‑night salivary cortisol | Between 11:00 pm and midnight | Reflects the nadir; loss of low‑night values is a hallmark of Cushing’s. |
| 24‑hour UFC | Collect all urine over a full day, starting after the first void | Provides an integrated measure; requires accurate timing and volume recording. |
| Serum DHEA‑S | Any time of day (preferably same time as cortisol if drawn together) | Minimal diurnal variation; consistency improves comparability. |
| ACTH stimulation | Baseline draw, then 30‑ and/or 60‑minute post‑cosyntropin draws | Fixed intervals ensure reproducibility. |
| DST | Evening dose of dexamethasone (around 11:00 pm), cortisol drawn next morning (8:00 am) | Aligns with the natural cortisol nadir for optimal suppression detection. |
Key considerations:
- Fasting status is not required for cortisol or DHEA‑S, but a light, non‑fatty meal is advisable to avoid post‑prandial lipemia that can interfere with some immunoassays.
- Stressful events (e.g., acute illness, major surgery, severe emotional stress) can transiently elevate cortisol; defer testing until the patient is clinically stable, unless the acute stress is the very reason for evaluation.
- Medications that affect steroid metabolism (e.g., oral contraceptives, anticonvulsants, antifungals, glucocorticoids) must be documented; some may necessitate alternative testing strategies or a washout period.
Pre‑Analytical Pitfalls and How to Avoid Them
- Sample handling
- Serum should be allowed to clot for 30 minutes, then centrifuged; plasma (EDTA) is acceptable for some assays but may affect DHEA‑S results.
- Saliva collection devices must be stored at 4 °C and processed within 24 hours to prevent bacterial degradation of cortisol.
- Cross‑reactivity
- Immunoassays for cortisol can cross‑react with cortisone, prednisone, and other synthetic steroids. When patients are on exogenous glucocorticoids, consider liquid chromatography‑tandem mass spectrometry (LC‑MS/MS) for specificity.
- Urine collection errors
- Incomplete 24‑hour collections (missed voids) underestimate UFC. Provide clear written instructions and a collection container with a volume marker.
- Diurnal variation
- For single‑point serum cortisol, ensure the draw is truly “morning.” A draw after 10 am can miss the peak and lead to false‑low interpretation.
- Biological variability
- Cortisol exhibits intra‑individual coefficient of variation of ~10 %. When borderline results are obtained, repeat testing on a different day is advisable.
Interpreting Results in Clinical Context
| Result Pattern | Likely Interpretation | Next Step |
|---|---|---|
| Low morning cortisol (< 5 µg/dL) + low DHEA‑S | Primary adrenal insufficiency or chronic glucocorticoid suppression | Perform ACTH stimulation test; assess ACTH level; consider adrenal antibodies. |
| Elevated morning cortisol (> 20 µg/dL) + suppressed ACTH | ACTH‑independent Cushing’s (adrenal adenoma/carcinoma) | Order adrenal imaging; consider low‑dose DST for confirmation. |
| Elevated cortisol with normal ACTH | ACTH‑dependent Cushing’s (pituitary or ectopic) | Proceed to high‑dose DST or CRH test; pituitary MRI if indicated. |
| Normal cortisol but low DHEA‑S | Age‑related decline or adrenal hypofunction; may correlate with reduced well‑being | Evaluate for chronic stress, medication effects; consider repeat testing if symptomatic. |
| High DHEA‑S with normal cortisol | Possible adrenal hyperandrogenism (e.g., adrenal hyperplasia, tumor) | Assess for clinical signs of androgen excess; consider imaging. |
| Discordant results (e.g., high cortisol, low DHEA‑S) | May reflect selective zona fasciculata hyperactivity; consider mixed pathology | Comprehensive endocrine work‑up; repeat testing with LC‑MS/MS for accuracy. |
Important nuance: A single abnormal value rarely clinches a diagnosis. Correlate with clinical signs, other laboratory parameters (electrolytes, glucose, ACTH), and imaging when appropriate.
Follow‑Up Strategies After an Abnormal Screen
- Confirmatory testing – Repeat the initial assay on a separate day or use a different specimen type (e.g., salivary cortisol if serum was abnormal).
- Dynamic testing – Deploy ACTH stimulation or DST based on the pattern of abnormality.
- Imaging – If autonomous secretion is confirmed, order adrenal CT/MRI or pituitary MRI as indicated.
- Referral – Endocrinology consultation is warranted for any result suggestive of Cushing’s syndrome, primary adrenal insufficiency, or unexplained androgen excess.
- Monitoring – For patients on chronic glucocorticoids, schedule periodic morning cortisol checks (e.g., every 3–6 months) to detect HPA axis suppression early.
Special Populations: Adjustments to the Screening Algorithm
| Population | Considerations | Recommended Modifications |
|---|---|---|
| Pregnant women | Elevated cortisol due to increased cortisol‑binding globulin (CBG); DHEA‑S may rise modestly. | Use UFC or late‑night salivary cortisol; interpret serum cortisol with caution. |
| Pediatric patients | Higher baseline cortisol; DHEA‑S rises after adrenarche (≈ 6–8 years). | Age‑specific reference ranges; consider ACTH stimulation for suspected insufficiency. |
| Elderly (> 65 y) | Physiologic decline in DHEA‑S; cortisol rhythm may flatten. | Focus on clinical symptoms; use UFC or salivary cortisol for Cushing’s screening. |
| Patients on oral contraceptives | ↑ CBG → higher total cortisol; DHEA‑S may be modestly increased. | Prefer free cortisol measurements (UFC, salivary) or LC‑MS/MS for total cortisol. |
| Renal or hepatic impairment | Altered metabolism and clearance of steroids; UFC may be falsely low. | Rely on serum or salivary cortisol; interpret UFC with caution. |
Practical Tips for Clinicians Implementing Routine Screening
- Standardize the order set – Create a pre‑configured electronic health record (EHR) panel that includes morning cortisol, DHEA‑S, and a brief medication checklist.
- Educate the patient – Provide a one‑page handout outlining fasting, timing, and medication considerations. Clear communication reduces pre‑analytical errors.
- Leverage laboratory partnerships – Work with the lab to ensure LC‑MS/MS availability for cases where immunoassay cross‑reactivity is a concern.
- Document the clinical rationale – Insurance payers often require justification; a concise note stating “evaluation of unexplained fatigue and weight change” can prevent claim denials.
- Track trends – Use a longitudinal view in the EHR to plot cortisol and DHEA‑S over time; visual trends aid in decision‑making.
- Cost‑effectiveness – For low‑risk patients, start with a single morning cortisol; reserve more expensive 24‑hour UFC or salivary panels for those with high pre‑test probability of pathology.
Communicating Results to Patients
- Normalize the variability – Explain that cortisol naturally fluctuates and that a single abnormal value does not always mean disease.
- Link to symptoms – Tie any abnormal findings to the patient’s specific complaints (e.g., “Your low morning cortisol may explain the fatigue you’ve been feeling”).
- Outline next steps – Provide a clear roadmap: repeat test, possible dynamic testing, or referral.
- Reassure – Emphasize that most abnormalities are manageable and that early detection improves outcomes.
Key Takeaways
- Indications matter: Test cortisol and DHEA when clinical clues point to adrenal dysfunction—unexplained weight change, refractory hypertension, electrolyte disturbances, androgen excess, or known adrenal lesions.
- Timing is critical: Morning serum cortisol (7–9 am) and late‑night salivary cortisol capture the diurnal extremes; DHEA‑S can be drawn at any time but should be consistent.
- Choose the right assay: Start with static measurements; move to dynamic tests (ACTH stimulation, DST) only when the initial result is ambiguous or when functional assessment is required.
- Mind the pre‑analytical variables: Medications, acute stress, collection errors, and assay cross‑reactivity can all skew results.
- Interpret in context: Combine hormone levels with clinical presentation, other labs, and imaging before arriving at a diagnosis.
- Plan follow‑up: Confirm abnormal screens, use dynamic testing as needed, and involve endocrinology for definitive management.
- Tailor to the individual: Adjust protocols for pregnancy, children, the elderly, and patients on hormone‑affecting drugs.
By integrating these practical guidelines into routine practice, clinicians can efficiently screen for adrenal hormone abnormalities, avoid unnecessary testing, and ensure that patients receive timely, accurate diagnoses that guide appropriate therapeutic interventions.
