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Serum or Plasma Free Cortisol (24-Hour Urinary Excretion)

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

This test measures the amount of cortisol naturally excreted in your urine over a full day. Cortisol is a hormone produced by your adrenal glands that helps regulate stress, metabolism, and immune response.

Quick summary

["Helps diagnose conditions like Cushing’s syndrome or adrenal gland issues by tracking cortisol levels over time."]

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

Key facts at a glance

LOINC
7480-7
Short code
Red Maple BasoBnd Ab Qn
Synonyms
Red Maple BasoBnd Ab Qn
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lhr
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters for Your Health

Cortisol is a key hormone that your body releases in response to stress. While small amounts are normal, too much over time can lead to health problems. This test checks how much cortisol your body eliminates in urine, which can reveal imbalances that might not show up in blood tests alone.

What to Expect Before the Test

You’ll collect your urine for 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 room temperature container, keeping all samples together. Some labs may provide a 24-hour urine collection kit to simplify the process.

How the Test Works

Your collected urine is sent to a lab where it’s analyzed to measure cortisol levels. The test looks at the total cortisol excreted in your urine, which reflects your body’s natural cortisol production over the day.

Possible Causes of Abnormal Results

High levels might suggest conditions like Cushing’s syndrome (too much cortisol), certain tumors, or prolonged stress. Low levels could indicate adrenal insufficiency, pituitary issues, or medications that affect cortisol.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urinary Free Cortisol

Frequently asked questions

How often should I expect this test?
This test is typically ordered as a one-time or follow-up test, depending on your symptoms or medical history. Your healthcare provider will let you know if you need to repeat it.
What do my results mean?
Results are usually reported as the total amount of cortisol excreted in urine over 24 hours. While reference ranges can vary by lab, abnormal results may prompt further testing or evaluation by your doctor.
Can I take my usual medications before this test?
Some medications, like certain steroids or blood pressure drugs, may affect cortisol levels. Always inform your doctor or lab technician about all medications 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