Cortisol concentration (serum/plasma)
This test measures the amount of cortisol, a natural steroid hormone produced by your adrenal glands, in your blood. Cortisol helps regulate metabolism, immune response, and stress reactions.
["Cortisol helps manage stress and supports normal bodily functions, and this test helps assess adrenal gland health or hormone imbalances."]
Key facts at a glance
- LOINC
- 58636-2
- Short code
- Cortis 10 PM SerPl-sCnc
- Synonyms
- Cortis 10 PM SerPl-sCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Doctors may order cortisol tests to diagnose or monitor conditions like adrenal gland disorders (such as Cushing’s syndrome or Addison’s disease), evaluate stress responses, or check for hormonal imbalances. It can also help assess pituitary gland function or rule out certain metabolic issues.
What to Expect Before the Test
No special preparation is needed for this test, but you may be asked to fast for 8–12 hours before drawing blood. If you’re taking medications that affect cortisol levels, your doctor will let you know if you should stop them temporarily or adjust timing.
What Happens During the Test
A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab for analysis, where cortisol concentration is measured using a sensitive immunoassay method. The result is typically available within 1–3 business days.
What the Results Mean
Results are compared to general reference ranges, but your actual values may vary based on factors like time of day, stress levels, and medications. High cortisol levels may indicate overactivity of the adrenal glands or Cushing’s syndrome, while low levels could signal adrenal insufficiency or pituitary issues.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cortisol levels are critical for diagnosing conditions like adrenal insufficiency (Addison’s disease), Cushing’s syndrome, or evaluating stress-related symptoms. Abnormal results may prompt further testing, such as a 24-hour urine cortisol test or a dexamethasone suppression test, to confirm a diagnosis.
Short name
Serum/plasma cortisol level
Frequently asked questions
What causes cortisol levels to be too high?
What causes cortisol levels to be too low?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy