🌡️ Adrenal & Cortisol Axis

What this panel can settle, and by what logic

This panel exists to find the real conditions that produce the symptoms ‘adrenal fatigue’ is used to describe. Three of them are genuinely settled here, and each one needs two markers together.

1. Cortisol (AM) with ACTH (Adrenocorticotropic Hormone) localizes the problem to a gland. A low 8am cortisol with a HIGH ACTH is primary adrenal insufficiency: the gland is failing and the pituitary is shouting at it, which is why the two have to come out of the same 30 minutes. A low cortisol with a low or inappropriately normal ACTH is secondary, and points at the pituitary or at exogenous steroid. Cortisol alone cannot tell those apart and they are different diseases Ramadoss 2021.
2. Cortisol (AM) with the Comprehensive Metabolic Panel (CMP) catches the dangerous direction. Primary adrenal insufficiency classically drags sodium below 135 mmol/L and pushes potassium above 5.0 mmol/L, because aldosterone fails alongside cortisol; the Aldosterone on this panel is what confirms it.
3. DHEA-S with Pregnenolone measures adrenal output rather than adrenal stress. DHEA-S is the most abundant circulating adrenal steroid and falls steadily with age, so a result that reads low against a 25 year reference is the ordinary finding by the age of 55 years and means nothing on its own Erceg 2025.

TSH (Thyroid-Stimulating Hormone) and Ferritin are on this panel for the same reason a good clinician checks them: hypothyroidism and iron deficiency reproduce the entire ‘wired and tired’ presentation and are far more common than anything adrenal.

What it cannot settle, and what would

It cannot diagnose ‘adrenal fatigue’, because there is nothing to diagnose. Adrenal fatigue is catalogued in the endocrine literature as a pseudo-endocrine disorder — a real symptom set attached to a mechanism that does not exist McDermott 2024. No pattern of cortisol, DHEA-S or pregnenolone on this panel establishes it, and a practitioner who reads ‘stage 2 adrenal fatigue’ off these numbers is reading something that is not there.

A single morning Cortisol (AM) cannot exclude adrenal insufficiency. Even a threshold built for the job runs at 59.5% specificity Ramadoss 2021, and the test that settles it is a short synacthen test: 250 mcg of synthetic ACTH, with cortisol measured at 0 and 30 minutes, done in a clinic. This panel tells you whether you need one; it is not one.

It cannot exclude Cushing syndrome either. Cortisol excess is diagnosed on a urinary free cortisol collected over 24 hours, on a late-night salivary cortisol or a dexamethasone suppression test, and a single morning serum value is not one of the three Flowers 2023.

And a raised ACTH (Adrenocorticotropic Hormone) is not always a raised ACTH. Plasma ACTH is fragile, degrades in an incorrectly handled tube, and has documented assay interference producing falsely elevated values Yang 2022. An isolated high ACTH with a normal cortisol is a reason to repeat the test, not a diagnosis.

Draw conditions that decide whether the money is wasted

More of this panel is destroyed by the draw than by anything else on the site, because two of its markers have a steep daily rhythm and one of them is fragile in the tube.

1. Cortisol (AM) and ACTH (Adrenocorticotropic Hormone) between 7 and 9am. Both peak in first 60 minutes after waking and fall through the day, so an afternoon pair cannot be read against a morning reference interval at all Ramadoss 2021. A 2pm cortisol of 180 nmol/L is uninformative; the same value at 8am is a finding.
2. ACTH needs the right tube, on ice, and spun inside 30 minutes. This is the marker most often reported wrongly for purely pre-analytical reasons Yang 2022, so if the result surprises everybody, repeat it before acting.
3. Tell them about every steroid. Prednisone, hydrocortisone, inhaled and topical steroids and even a joint injection suppress the axis, and a suppressed axis on this panel looks exactly like disease Flowers 2023.
4. No biotin for 72 hours Li 2020, and note the day of your cycle if you are cycling — Pregnenolone and DHEA-S are read against sex- and age-specific intervals Erceg 2025.

How you would know it answered your question, and what each pattern means next

Four patterns. One of them is urgent and the other three are not.

• Low 8am Cortisol (AM) with a high ACTH (Adrenocorticotropic Hormone): primary adrenal insufficiency until disproven. This goes to a doctor within days, not weeks — it is the one finding in this panel that is dangerous untreated Ramadoss 2021.
• Low Cortisol (AM) with a low or normal ACTH (Adrenocorticotropic Hormone): secondary. The next test is pituitary: Prolactin, TSH (Thyroid-Stimulating Hormone) with Free T4 (Thyroxine), IGF-1 (Insulin-like Growth Factor 1) and LH & FSH, because a pituitary that has stopped making one hormone rarely stops at one Flowers 2023.
• High Aldosterone with a potassium under 3.5 mmol/L on the Comprehensive Metabolic Panel (CMP): ask for an aldosterone-to-renin ratio and an endocrinology referral. This is a treatable cause of hypertension and it is missed constantly.
• Everything normal, symptoms unchanged: that is the expected result, and it is the useful one. The axis is not the problem McDermott 2024; sleep, iron, thyroid and mood are where the answer usually is, and repeating cortisol in 6 weeks will produce another normal number.

Sources read for these sections

• Ramadoss V, et al. Improving the Interpretation of Afternoon Cortisol Levels and SSTs to Prevent Misdiagnosis of Adrenal Insufficiency. Journal of the Endocrine Society 2021 · PMID 34611573
• McDermott MT. Pseudo-endocrine Disorders: Recognition, Management, and Action. Journal of the Endocrine Society 2024 · PMID 39749108
• Flowers KC, et al. Pitfalls in the Diagnosis and Management of Hypercortisolism (Cushing Syndrome) in Humans; A Review of the Laboratory Medicine Perspective. Diagnostics (Basel) 2023 · PMID 37189516
• Yang YY, et al. A Pitfall of Falsely Elevated ACTH: A Case Report and Literature Review. Journal of Investigative Medicine High Impact Case Reports 2022 · PMID 35699218
• Erceg N, et al. The Role of Cortisol and Dehydroepiandrosterone in Obesity, Pain, and Aging. Diseases 2025 · PMID 39997049
• Li D, Ferguson A, Cervinski MA, Lynch KL, Kyle PB. AACC Guidance Document on Biotin Interference in Laboratory Tests. J Appl Lab Med 2020 · PMID 32445355