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Cortisol, Free Serum (24-Hour Urinary Excretion)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of free cortisol naturally excreted in your urine over a 24-hour period. Free cortisol is the active form of cortisol, a hormone produced by your adrenal glands that helps regulate metabolism, immune response, and stress reactions.

Quick summary

["Assessing your natural cortisol levels over time to check for hormonal imbalances or adrenal function."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
60681-4
Short code
Cortis F 1h p ACTH SerPl-mCnc
Synonyms
Cortis F 1h p ACTH SerPl-mCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
60
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 Matters

Cortisol plays a key role in managing stress, immune function, and energy levels. Measuring free cortisol in urine helps doctors diagnose conditions like Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol).

What to Expect Before the Test

You’ll collect all urine for a full 24 hours, starting right after you wake up and ending just before you wake up the next day. Store the urine in a refrigerator or freezer to keep it fresh. Your doctor or lab technician will provide detailed instructions.

How the Test Works

The test involves analyzing your urine sample for cortisol, which is naturally present in small amounts. The lab measures the total cortisol excreted over the day to reflect your body’s natural production and balance.

Possible Causes for Testing

Your doctor may recommend this test if you have symptoms like unexplained weight gain, fatigue, high blood pressure, or unusual hair growth. It’s also used to evaluate conditions like adrenal tumors, pituitary disorders, or chronic stress-related hormone imbalances.

Reference range

NCBI: ACTH 10-60 pg/mLN/A

Specimen: serum

Typically collected in the morning (8-10 AM). Inform your provider if taking steroid medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Frequently asked questions

How long does it take to get the results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will discuss the results with you during your follow-up appointment.
What do my results mean?
Results are compared to standard ranges for healthy adults. Abnormally high or low levels may indicate hormonal imbalances or underlying health conditions that need further medical evaluation. Your doctor will interpret the results in the context of your symptoms and medical history.
Can I take medications before the test?
Some medications, like certain steroids or blood pressure drugs, may affect cortisol levels. Your doctor will provide specific instructions on whether to stop or adjust medications 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 17, 2026. · Read our editorial policy