Skip to content

Cortisol, Serum (Free Cortisol)

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

This test measures the amount of free cortisol, a form of the hormone cortisol, in your blood. Free cortisol is the active, non-protein-bound form that circulates freely in your bloodstream and is important for regulating stress responses and other bodily functions.

Quick summary

["Free cortisol helps your body manage stress and maintain balance in your hormones."]

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

Key facts at a glance

LOINC
50415-9
Short code
Cortis pre 2 mg Dex SerPl-mCnc
Synonyms
Cortis pre 2 mg Dex SerPl-mCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82670
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 healthcare provider may order this test to diagnose or monitor conditions related to abnormal cortisol levels, such as Cushing’s syndrome (too much cortisol), adrenal insufficiency (too little cortisol), or to assess how your body responds to stress or medications like steroids.

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 drawing blood. If you’re taking medications that affect cortisol levels, let your provider know. Avoid caffeine or stress before the test if instructed.

How the Test Is Performed

A blood sample is taken from a vein in your arm by a healthcare professional. The blood is then sent to a lab for analysis to measure free cortisol levels.

What the Results Mean

Results are compared to standard reference ranges for free cortisol in serum. High or low levels may indicate underlying health issues that need further evaluation, such as hormonal imbalances or conditions affecting your adrenal glands.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/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.

◆Associated findings1

Short name

Free Cortisol

Frequently asked questions

What causes my cortisol levels to be tested?
Your doctor may recommend this test if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or signs of excess cortisol (e.g., weight gain in the upper body) or adrenal problems (e.g., low energy, dizziness). It’s also used to evaluate responses to stress or medications.
How long will I need to wait for my results?
Results are typically available within 1–3 business days, depending on your lab. Your healthcare provider will discuss them with you during your follow-up visit.
Can I take anything special before this test?
Follow your provider’s instructions, but generally, avoid caffeine or heavy meals for 8–12 hours before testing. If you’re on medications like steroids, let your doctor know to avoid interfering with 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 16, 2026. · Read our editorial policy