Cortisol: What Your Result Means
Result guide · Endocrine
Content last reviewed 2026-09-12 · Educational information — not medical advice
Quick answer
Cortisol follows a daily arc — morning peaks, midnight troughs. Interpreting ANY value requires knowing the draw TIME. Random afternoon cortisols generate endless false alarms; midnight salivary and morning serum values carry diagnostic weight.
What is Cortisol?
Adrenal cortex secretes cortisol pulsatile-diurnally under ACTH control, peaking ~30-45 min after waking (cortisol awakening response), troughing around midnight. Functions span glucose mobilization, blood pressure support, immune modulation, and stress response — the 'get up and survive' hormone.
Typical reference interval: Morning (8am) ~5–23 µg/dL; evening ~50-70% lower; midnight salivary <~1.5 ng/mL (suppression expected).. Laboratories differ — the interval printed on YOUR report always governs.
If your Cortisol is high
Common reasons Cortisol runs above the reference interval:
- Time-of-collection artifact — stressful draws, post-workout, shift-worker circadian inversion
- Cushing syndrome — endogenous — screening uses midnight salivary ×2, low-dose dexamethasone suppression, or 24h urine free cortisol
- Exogenous steroids — creams, inhalers, injections ALL suppress axes — not just pills
- Depression/alcoholism/obesity — 'pseudo-Cushing' mild elevations reversing with the underlying condition
- Estrogen states — raise CBG raising TOTAL cortisol — free fraction unchanged
If your Cortisol is low
Common reasons Cortisol runs below the reference interval:
- Adrenal insufficiency — Addison's (primary, with HIGH ACTH + pigmentation + hyperkalemia) vs secondary (pituitary, with LOW ACTH)
- Steroid withdrawal — HPA-axis suppression after prolonged exogenous steroids — tapering exists for this reason
- Congenital adrenal hyperplasia — enzyme blocks
- Random afternoon draws — physiologically low anyway — the sampling trap
Symptoms worth knowing
Excess: central weight gain, moon facies, purple striae, proximal weakness, hypertension, hyperglycemia, osteoporosis, easy bruising. Deficiency: profound fatigue, weight LOSS, nausea, hypotension, hyperpigmentation (primary), salt craving — adrenal crisis (vomiting + shock) is the emergency.
What usually happens next
Get your Cortisol checked
These lab tests measure Cortisol directly. Ordering online takes a few minutes and results arrive securely.
We may earn a commission when you order through partner links on the following pages. Educational information here never replaces advice from a qualified healthcare provider.
Panels that include this value
Cortisol appears as one line inside these broader panels — better value than ordering single markers alone:
Related result guides
Frequently asked questions about Cortisol results
Can I test cortisol while on birth control?
Estrogen raises CBG inflating TOTAL cortisol readings — salivary or free-cortisol methods sidestep this. Flag contraception when ordering.
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