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Free Cortisol (Serum)

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

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

Quick summary

["Free cortisol helps evaluate adrenal function and hormone balance."]

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

Key facts at a glance

LOINC
110419-9
Short code
Cortisone free Msmt Ur
Synonyms
Cortisone free Msmt Ur
Category
chemistry
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 a free cortisol test to check for conditions like Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol). It can also help diagnose hormonal imbalances or rule out certain adrenal or pituitary disorders.

What Does It Measure?

Free cortisol is the active, unbound form of cortisol in your blood. Unlike total cortisol, which includes both free and protein-bound forms, free cortisol reflects your body’s immediate hormone levels more accurately.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The sample is processed to separate the free cortisol from other proteins. This test is typically done in the morning when cortisol levels are naturally highest.

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 have a history of bleeding disorders, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Cortisol

Frequently asked questions

How is this test different from total cortisol?
Free cortisol is measured separately to focus on the biologically active portion of cortisol in your blood, while total cortisol includes both free and protein-bound forms. Free cortisol testing is often preferred for more precise diagnosis of hormonal imbalances.
Can stress affect my free cortisol levels?
Yes, stress can temporarily raise cortisol levels. If your test is done during a stressful period, results may not reflect your baseline hormone levels. Your doctor may recommend testing during a calmer time or additional tests to interpret results accurately.
What conditions might lead to abnormal free cortisol results?
Conditions like Cushing’s syndrome, adrenal tumors, pituitary tumors, or chronic stress can cause elevated free cortisol. Conversely, adrenal insufficiency, Addison’s disease, or certain medications (e.g., steroids) may lead to lower levels. Always discuss symptoms and medical history with your doctor.
  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