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Cortisol, Serum (Mass Concentration)

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

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

Quick summary

["Cortisol levels can help diagnose adrenal gland issues or stress-related conditions."]

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

Key facts at a glance

LOINC
50455-5
Short code
Cortis sp3 SerPl-mCnc
Synonyms
Cortis sp3 SerPl-mCnc
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 healthcare provider may order cortisol testing to check for conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or to evaluate how your body responds to stress or medications that affect cortisol levels.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The sample is sent to a lab for analysis to measure cortisol concentration in your serum.

What Are Common Uses?

Cortisol testing is often used in combination with other tests (like ACTH stimulation tests) to diagnose hormonal imbalances or adrenal dysfunctions. It may also be checked during pregnancy or to monitor chronic stress responses.

What Might Affect Results?

Factors like time of day (cortisol levels naturally rise in the morning), recent stress, certain medications (e.g., steroids), or timing around meals can influence cortisol levels. Always follow your provider’s instructions for fasting or timing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Cortisol is essential for managing stress, immune function, and metabolism. Abnormally high or low levels can cause symptoms like fatigue, weight changes, mood swings, or unexplained muscle weakness. Chronic stress or medical conditions like Cushing’s or Addison’s disease can lead to persistent imbalances.

Short name

Serum Cortisol

Frequently asked questions

Why was cortisol testing ordered for me?
Your provider may have suspected adrenal gland problems, stress-related hormone issues, or other conditions affecting cortisol production or regulation. They might also be checking for Cushing’s syndrome, Addison’s disease, or evaluating how your body handles cortisol during stress.
What should I do to prepare for this test?
If instructed, avoid caffeine or stress for a few hours before testing. Fast for 8–12 hours if required (check with your provider). Wear loose clothing for the blood draw and stay hydrated unless advised otherwise.
Will I feel pain or discomfort during the blood draw?
You may feel a slight pinch or sting when the needle is inserted, but most people describe it as mild. Afterward, there may be a small bruise or soreness at the site. Tell your provider if you experience excessive pain or swelling.
  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