Skip to content

Free Cortisol (Serum)

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

This test measures the amount of cortisol (a natural steroid hormone) that is *not* bound to proteins in your blood, helping assess how well your body regulates stress hormones.

Quick summary

["Free cortisol helps diagnose 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
49029-2
Short code
Cortis F/Cortisone Free Ur
Synonyms
Cortis F/Cortisone Free Ur
Category
hormone
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order free cortisol testing if you have symptoms of hormonal imbalances, such as unexplained weight changes, high blood pressure, or unusual fatigue. It’s also used to evaluate conditions like Cushing’s syndrome (too much cortisol) or adrenal gland disorders.

How Is the Sample Collected?

A blood sample is taken from a vein in your arm. You may feel a slight pinch, but it’s usually over quickly. The sample is sent to a lab for analysis.

What Does the Result Mean?

Results are interpreted based on your symptoms and other tests. Elevated levels may suggest Cushing’s syndrome or adrenal tumors, while low levels could indicate adrenal insufficiency or pituitary issues. Your doctor will discuss findings with you.

Common Conditions Linked to Free Cortisol

High free cortisol is often linked to conditions like Cushing’s syndrome (caused by prolonged high cortisol from tumors or medications). Low levels may signal adrenal gland problems, such as Addison’s disease, or issues with the pituitary gland.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Free Cortisol Testing

Short name

Free Cortisol

Frequently asked questions

How long does it take to get my results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready.
What should I do if my results are abnormal?
If your free cortisol levels are outside the expected range, your doctor may recommend additional tests (like a 24-hour urine cortisol test) or further evaluation to identify the cause. Follow-up may include imaging or hormone stimulation/suppression tests.
Can I eat or drink before this test?
No special preparation is needed for this blood test. However, avoid caffeine or alcohol for 24 hours before testing, as they may 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