Skip to content

Cortisol, Mass Concentration in Serum/Plasma

Published: August 9, 2026Updated: August 17, 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 levels can indicate how your body handles stress or help diagnose conditions like Cushing’s syndrome or adrenal insufficiency."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
48102-8
Short code
Cortis 4 AM specimen SerPl-mCnc
Synonyms
Cortis 4 AM specimen SerPl-mCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
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 Is This Test Done?

Your doctor may order cortisol testing to check for hormonal imbalances, evaluate symptoms of stress or fatigue, or diagnose conditions like Addison’s disease, Cushing’s syndrome, or pituitary disorders. It can also be used to monitor treatment effectiveness for these conditions.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast (not eat or drink) for 8–12 hours before the test if timing your results around natural cortisol peaks (e.g., morning or evening). If you’re taking medications, let your provider know.

What Happens During the Test?

A blood sample is drawn from a vein, typically in your arm. The sample is sent to a lab for measurement using a sensitive immunoassay technique to detect cortisol levels accurately.

What Do Results Mean?

Results are compared to reference ranges, but individual ranges can vary by lab. High cortisol levels may suggest overproduction (e.g., from tumors or chronic stress), while low levels may indicate underproduction (e.g., adrenal failure). Your doctor will interpret results in the context of your symptoms and medical history.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum/Plasma Cortisol

Frequently asked questions

What causes cortisol levels to be tested?
Cortisol testing is often done to diagnose or monitor conditions such as Cushing’s syndrome (excess cortisol), Addison’s disease (low cortisol), or to assess stress-related symptoms like fatigue, weight changes, or mood disorders. It may also be used in research or specialized cases to evaluate circadian rhythms or adrenal function.
How do cortisol levels change throughout the day?
Cortisol follows a natural daily rhythm, typically peaking in the early morning and declining by evening. Some tests measure cortisol at specific times (e.g., morning or evening) to detect abnormalities in this pattern, while others provide a single snapshot of your level.
Can cortisol levels be affected by medications or lifestyle?
Yes. Medications like steroids (e.g., prednisone) can raise cortisol levels, while some antidepressants or blood pressure drugs may lower them. Lifestyle factors like chronic stress, sleep patterns, or alcohol use can also influence cortisol levels, so your doctor may consider these when interpreting results.
  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 17, 2026. · Read our editorial policy