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Cortisol, Serum, Free (24-Hour Urinary)

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

This test measures the amount of free cortisol, a form of the hormone cortisol, excreted in your urine over a 24-hour period. It helps assess your body’s cortisol production and adrenal gland function.

Quick summary

["This test helps diagnose conditions related to cortisol imbalance, such as Cushing’s syndrome or adrenal insufficiency."]

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

Key facts at a glance

LOINC
16675-1
Short code
Cortis 80M p chal SerPl-mCnc
Synonyms
Cortis 80M 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 doctor may order this test if they suspect conditions like Cushing’s syndrome (overproduction of cortisol) or adrenal gland disorders. It can also be used to monitor treatment for these conditions or evaluate stress responses.

What to Expect Before the Test

You’ll need to collect a 24-hour urine sample starting from one morning after waking up and continuing until the same time the next day. Store the urine in a refrigerator or freezer to preserve it. Follow your doctor’s instructions carefully for accurate results.

What the Test Results Mean

Results are interpreted by your healthcare provider based on your medical history and symptoms. Abnormally high or low levels may indicate hormonal imbalances that require further evaluation.

Common Conditions This Test Helps Diagnose

This test is particularly useful for diagnosing conditions like Cushing’s syndrome (caused by excess cortisol) or primary adrenal insufficiency (Addison’s disease), where cortisol levels may be too low.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Cortisol (Urine)

Frequently asked questions

How is the urine sample collected?
You’ll start collecting urine immediately after waking up on the first morning. Use a clean container and collect all urine for 24 hours, including during sleep. Discard the first morning urine and begin collecting from the second void. Store the sample in a cool place until you return it to the lab.
What should I do if I miss any urine during the 24-hour period?
If you miss any urine, try to catch it in a container and add it to your sample. If you’re unable to complete the full 24 hours, contact your lab or doctor to discuss adjustments.
Can I take medications that might affect cortisol levels?
Some medications, like steroids or certain antidepressants, can influence cortisol levels. Always inform your doctor or lab technician about all medications, supplements, or herbal products you’re taking before the test.
  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