Cortisol Test
A cortisol test measures the stress hormone levels in your blood to assess adrenal gland function and your body's response to stress.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
A cortisol test measures the blood level of cortisol, a steroid hormone produced by the adrenal glands. Cortisol is central to the body's stress response, but its influence extends well beyond that: it participates in glucose metabolism, immune regulation, blood pressure maintenance, and the sleep-wake cycle. Production is governed by a hormonal cascade: the hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary gland to secrete adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal glands to produce cortisol.
Cortisol follows a predictable daily rhythm called diurnal variation. Levels peak in the early morning (typically between 6 and 8 AM) and gradually taper throughout the day, reaching their lowest point around midnight. Most circulating cortisol is bound to cortisol-binding globulin and albumin; normally less than 5% remains free and biologically active. The test helps healthcare providers determine whether the adrenal glands are producing cortisol within the expected range and can identify overproduction or underproduction that may be affecting energy, immunity, or metabolic function.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing chronic fatigue, unexplained weight changes, or persistent low energy levels
- People dealing with prolonged stress, anxiety, or difficulty managing daily pressures
- Those with symptoms like mood swings, irritability, or feeling overwhelmed by everyday situations
- Individuals experiencing sleep disturbances, difficulty falling asleep, or waking up feeling unrefreshed
- People with unexplained changes in blood pressure, blood sugar, or immune function
- Those with symptoms that may suggest adrenal disorders, such as muscle weakness or unusual skin changes
- Individuals curious about how their body responds to stress or wanting to establish baseline hormone levels
What to expect
Preparation
No special preparation is needed, though you should avoid vigorous exercise and try to minimize stress before your test. The timing of collection is important since cortisol levels vary throughout the day, so follow any specific instructions about when to have your blood drawn.
Sample Type
A simple blood draw from a vein in your arm, similar to any routine blood test
Collection
Visit any Quest or LabCorp location with your test requisition. No appointment needed at most locations. Bring a valid photo ID and your test paperwork
Turnaround
Results are typically available within 1-3 business days and will be delivered securely to your online account
Understanding your results
Cortisol reference ranges vary by laboratory and, critically, by the time of day the blood is drawn. A level that would be normal at 8 AM could be considered elevated at 4 PM. An out-of-range result does not automatically indicate a disorder; transient factors like acute stress, illness, medications, and sleep disruption can all shift cortisol levels temporarily. Healthcare providers interpret results in the context of symptoms, draw timing, and medical history, and may order additional testing (such as a 24-hour urinary cortisol or a stimulation test) to clarify the clinical picture.
| Population | Reference Range | Notes |
|---|---|---|
| Adults (morning 6-8 AM) | 10-20 mcg/dL | Peak cortisol levels occur in early morning |
| Adults (afternoon 4 PM) | 3-10 mcg/dL | Levels naturally decline throughout the day |
| Adults (evening/midnight) | <5 mcg/dL | Lowest levels occur late evening and overnight |
Reference ranges shown are general guidelines. Your lab report will include the specific reference range used by the laboratory that processed your sample, which is the authoritative range for interpreting your results.
What does a “Low” result mean?
Low cortisol levels may suggest Addison's disease, a condition that happens when your body doesn't have enough cortisol. In primary adrenal insufficiency, ACTH levels are increased and cortisol levels are decreased; in secondary adrenal insufficiency both ACTH and cortisol levels are decreased. Low levels can also indicate problems with pituitary gland function or may result from suddenly stopping steroid medications.
What does a “High” result mean?
High cortisol levels may indicate Cushing syndrome, which is characterized by increased serum cortisol levels. Very high levels of cortisol are usually a sign of Cushing's syndrome, which may be caused by taking large amounts of steroid medications or a tumor in your pituitary gland that produces adrenocorticotropic hormone (ACTH). Elevated levels can also result from chronic stress, certain medications, or other conditions affecting adrenal function.
Privacy & confidentiality
Your cortisol test results are delivered securely through your private online account and are never shared with employers, insurers, or anyone else without your explicit consent. All testing is completely confidential, and you control who sees your health information.
Frequently asked questions
Related tests
Related conditions
Last reviewed: April 2026
CPT Code: 82533
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
Not sure if this is the right test? Contact our care team for guidance.
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