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Cortisol, Serum (Free)

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

This test measures the amount of free (unbound) cortisol in your blood, a hormone produced by your adrenal glands that helps regulate stress responses, metabolism, and immune function.

Quick summary

["Free cortisol helps assess adrenal gland health and hormone balance, especially in 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
29358-9
Short code
Cortis pre chal SerPl-mCnc
Synonyms
Cortis pre chal 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 This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or signs of hormonal imbalances. It could also be used to diagnose or monitor conditions such as Cushing’s disease, adrenal tumors, or other adrenal-related disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid certain medications (like steroids) that could affect cortisol levels. If you’re taking them, let your provider know. You’ll have a simple blood draw, typically taken in the morning when cortisol levels are highest.

What the Results Mean

Results help determine if your cortisol levels are too high (hypercortisolism) or too low (hypocortisolism). Abnormal levels may indicate conditions requiring further evaluation or treatment.

Common Conditions This Test Helps Diagnose

This test is often used alongside other tests to diagnose conditions like Cushing’s syndrome (high cortisol), adrenal insufficiency (low cortisol), or to evaluate stress-related hormone imbalances.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Cortisol

Frequently asked questions

How long will it take to get my results?
Results are typically available within 1–3 business days, depending on your lab. Your provider will discuss them with you during your follow-up visit.
Can I eat or drink before the blood draw?
You can eat and drink normally before the test, but avoid alcohol for 24 hours before your appointment, as it may affect cortisol levels.
What if my cortisol levels are abnormal?
If your results are abnormal, your provider may recommend additional tests (like a 24-hour urine cortisol test or a dexamethasone suppression test) to confirm the 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