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Cortisol, Serum or Plasma Substance 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 gland health or hormone imbalances."]

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

Key facts at a glance

LOINC
14675-3
Short code
Cortis SerPl-sCnc
Synonyms
Cortis 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 Might This Test Be Done?

Your healthcare provider may order a cortisol test to diagnose or monitor conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or adrenal gland tumors. It can also help evaluate stress responses, hormone imbalances, or certain types of headaches.

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 early morning blood collection (morning cortisol levels are often checked). Avoid caffeine or stress-inducing activities for a few hours before testing.

How the Test Is Performed

A blood sample is drawn from a vein in your arm by a healthcare professional. The blood is then sent to a lab for analysis using a sensitive immunoassay method to measure cortisol concentration.

What the Results Mean

Results are compared to general reference ranges for cortisol levels in serum or plasma. Abnormally high or low levels may indicate underlying health conditions that require further evaluation by your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cortisol Level

Frequently asked questions

What causes cortisol levels to be too high?
High cortisol levels may be caused by conditions like Cushing’s syndrome (due to excess hormone production or tumors), prolonged stress, certain medications, or pituitary or adrenal gland tumors. Symptoms may include weight gain, fatigue, or muscle weakness.
What causes cortisol levels to be too low?
Low cortisol levels, or Addison’s disease, can result from autoimmune destruction of the adrenal glands, infections, or sudden withdrawal from steroid medications. Symptoms may include fatigue, low blood pressure, dizziness, or weight loss.
How often should I get this test?
Your doctor will determine the frequency based on your symptoms, medical history, and treatment plan. Regular monitoring may be needed if you have conditions like Cushing’s syndrome or adrenal insufficiency, or if you’re taking medications that affect 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