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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What this test measures
A cortisol test measures the level of cortisol in your blood. Cortisol is a hormone your adrenal glands make that affects several aspects of your health and helps regulate your body's response to stress. This hormone plays a central role in glucose metabolism and in the body's response to stress, with levels regulated by corticotropin (ACTH), which is synthesized by the pituitary gland in response to corticotropin-releasing hormone (CRH).
Cortisol follows a natural daily rhythm called diurnal variation, with levels typically highest in the early morning (6-8 AM) and gradually declining throughout the day to reach their lowest point around midnight. The majority of cortisol circulates bound to cortisol-binding globulin and albumin, with normally less than 5% being free (unbound) and biologically active. The test helps healthcare providers evaluate whether your adrenal glands are producing appropriate amounts of this essential hormone and can identify potential imbalances that may be affecting your overall health and well-being.
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
Normal cortisol ranges can vary from lab to lab, time to time and person to person, so your healthcare provider will interpret your results and let you know if you need to get further testing. Having a high or low level of cortisol doesn't necessarily mean you have a medical condition that needs treatment, as abnormal results don't automatically indicate a medical condition requiring treatment. The timing of your test is crucial since cortisol follows a natural daily rhythm, and your lab report will include the specific reference ranges used by the laboratory that processed your sample.
| 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
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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Not sure if this is the right test? Contact our care team for guidance.