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Cortisol (24-hour urinary free cortisol)

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

This test measures the amount of cortisol, a natural steroid hormone, excreted in your urine over a full day. It helps assess adrenal gland function and hormone balance.

Quick summary

["This test helps check if your adrenal glands are producing enough cortisol, which can affect stress responses and other bodily functions."]

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

Key facts at a glance

LOINC
21225-8
Short code
Cortis 3h p chal SerPl-mCnc
Synonyms
Cortis 3h p 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 Is Done

Your healthcare provider may order this test if you have symptoms like fatigue, weight changes, muscle weakness, or unexplained mood swings. It’s also used to diagnose conditions such as Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol).

What to Expect Before the Test

You’ll collect urine for 24 hours, starting and ending at the same time each day. Store the urine in a refrigerator or freezer until you bring it to the lab. Avoid certain medications that might affect results, like some blood pressure drugs.

During the Test

No special preparation is needed beyond collecting urine over 24 hours. The lab will analyze the sample to measure cortisol levels.

Possible Results and Interpretation

Results are compared to standard ranges, but exact values can vary by lab. High cortisol levels may indicate conditions like Cushing’s syndrome, while low levels could signal adrenal problems or other hormonal imbalances.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

24-Hour Urine Cortisol

Frequently asked questions

What does cortisol do in the body?
Cortisol is a hormone produced by your adrenal glands that helps regulate metabolism, immune response, and stress reactions. It’s naturally high in the morning and lower at night. Abnormal levels can affect energy, mood, and overall health.
How does this test differ from a blood cortisol test?
This test measures cortisol excreted in urine over a full day, giving a more comprehensive picture of your body’s cortisol production. A blood test checks cortisol levels at a single point in time, which may not reflect daily fluctuations.
Can diet or medications affect this test?
Yes, certain foods (like licorice or high-sodium diets) and medications (such as birth control pills or blood pressure drugs) can influence cortisol levels. Always inform your provider about all medications and dietary habits before testing.
  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