Skip to content

Serum or Plasma Endogenous Corticosteroid Concentration (Total Cortisol)

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; abnormal levels may signal health concerns."]

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

Key facts at a glance

LOINC
112011-2
Short code
Resecton type Endscpy
Synonyms
Resecton type Endscpy
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
endoscopy
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 to evaluate adrenal gland function, diagnose conditions like Cushing’s syndrome (too much cortisol) or Addison’s disease (too little cortisol), or check for issues with cortisol production or metabolism. It could also be used to monitor treatment for hormone-related disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. If you’re taking medications that affect cortisol levels (like steroids), let your doctor know.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm. The blood sample is then sent to a lab for analysis using an immunoassay method to measure cortisol levels.

What the Results Mean

Results are compared to standard reference ranges, but individual ranges can vary. High cortisol levels may indicate conditions like Cushing’s syndrome, while low levels could suggest Addison’s disease or other adrenal issues. Your doctor will interpret results in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Total Cortisol

Frequently asked questions

What does cortisol do in the body?
Cortisol is a key hormone involved in managing stress, immune response, and metabolism. It helps regulate blood pressure, blood sugar, and inflammation. Abnormal cortisol levels can lead to symptoms like weight changes, fatigue, muscle weakness, or unusual hair growth (in Cushing’s syndrome) or low blood pressure, dizziness, or darkening skin (in Addison’s disease).
How might abnormal cortisol levels affect my health?
High cortisol levels may cause long-term health risks like weakened bones, high blood pressure, or increased risk of type 2 diabetes. Low cortisol levels can lead to severe fatigue, salt and water retention, or even life-threatening conditions if untreated. Your doctor will work with you to address any imbalances.
Can cortisol levels change based on when I take the test?
Yes, cortisol levels naturally fluctuate throughout the day, with peaks in the morning and lower levels at night. If your test is for diagnostic purposes, your doctor may recommend specific timing (e.g., morning blood draw) or multiple tests to get an accurate picture of your cortisol levels.
  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