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Cortisol, Serum (Mass Concentration)

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

This test measures the amount of cortisol, a key hormone produced by your adrenal glands, in your blood serum. Cortisol helps regulate metabolism, immune response, and stress reactions.

Quick summary

["Cortisol levels help assess adrenal gland function and detect conditions like Cushing’s syndrome or adrenal insufficiency."]

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

Key facts at a glance

LOINC
24393-1
Short code
Cortis 10h p 1 mg Dex SerPl-sCnc
Synonyms
Cortis 10h p 1 mg Dex 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 Is This Test Done?

Your doctor may order a cortisol test to diagnose or monitor conditions affecting your adrenal glands, such as Cushing’s syndrome (too much cortisol) or Addison’s disease (too little cortisol). It can also help evaluate stress responses or hormone imbalances.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if timing cortisol levels around the same time of day is important. Bring any medications you’re taking to your doctor’s appointment.

What Happens During the Test?

A blood sample will be drawn from a vein in your arm by a healthcare professional. The sample is sent to a lab for analysis using a chemiluminescent immunoassay (ECLIA) method.

What Are Normal Results?

Results are not provided as a single numeric range here, as cortisol levels vary based on time of day and individual factors. Your doctor will interpret the results in relation to your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Cortisol Levels and Health

Short name

Serum Cortisol

Frequently asked questions

Why might my cortisol levels be checked?
If you have symptoms like unexplained weight changes, fatigue, high blood pressure, or muscle weakness, your doctor may recommend cortisol testing to rule out hormonal imbalances or adrenal disorders.
How do cortisol levels change with stress?
Cortisol naturally rises in response to stress, but consistently high or low levels can indicate underlying health issues. Your doctor may compare results at different times of day or under different conditions for better insight.
What if my cortisol test results are abnormal?
If results are outside expected ranges, further testing (such as a 24-hour urine cortisol test or a dexamethasone suppression test) may be needed to confirm a diagnosis and guide treatment.
  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