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Cortisol (Serum or Plasma) Concentration

Published: August 9, 2026Updated: August 16, 2026

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.

Quick summary

["Cortisol helps manage stress and supports normal bodily functions, and this test helps assess adrenal function or hormone imbalances."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
101586-6
Short code
Cortis SerPl LC/MS/MS-sCnc
Synonyms
Cortis SerPl LC/MS/MS-sCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lc-ms-ms
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 Might Be Ordered

Your doctor may recommend this test if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or signs of hormonal issues. It could also be used to diagnose conditions like Cushing’s syndrome, adrenal insufficiency, or to monitor treatment for conditions affecting hormone levels.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, typically in a doctor’s office or lab. If you’re taking medications that affect cortisol levels, your doctor will discuss this with you.

What the Test Results Mean

Results are interpreted based on your symptoms and medical history. High cortisol levels might suggest conditions like Cushing’s syndrome, while low levels could indicate adrenal gland problems or other hormonal disorders. Your doctor will discuss the results with you in the context of your overall health.

Common Conditions This Test Helps Diagnose

This test is often used to diagnose or monitor conditions such as adrenal gland disorders, including Addison’s disease (adrenal insufficiency) or Cushing’s syndrome (excess cortisol). It may also help evaluate stress responses or hormone imbalances in other contexts.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cortisol Level

Frequently asked questions

How is cortisol measured in this test?
Cortisol is measured using a blood sample collected from a vein. The test typically uses an immunoassay method to detect cortisol concentration in your serum or plasma. Results are reported as a mass concentration of cortisol.
What are typical reference ranges for cortisol?
Reference ranges vary by lab and individual factors like age, sex, and time of day. Your doctor will provide your specific results and compare them to your personal baseline or clinical context rather than a general range.
Can cortisol levels change based on when the blood sample is taken?
Yes, cortisol levels fluctuate throughout the day, with peaks in the morning and lower levels at night. If your test is for diagnosing conditions like Cushing’s syndrome, your doctor may ask for multiple samples at different times or use special testing protocols to capture these variations.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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