Skip to content

Cortisol Peak Concentration (24-Hour Urinary Free Cortisol)

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

This test measures the highest level of cortisol (a stress hormone) in your urine over a 24-hour period. It helps assess how your body produces and handles cortisol, often used to evaluate adrenal function or Cushing’s syndrome.

Quick summary

["Assesses cortisol production and potential adrenal issues over a full day."]

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

Key facts at a glance

LOINC
57824-5
Short code
Cortis F AM peak SerPl-mCnc
Synonyms
Cortis F AM peak 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 (excess cortisol), adrenal gland problems, or to monitor treatment for hormone-related disorders. It can also help diagnose or manage stress-related hormone imbalances.

What to Expect Before the Test

You’ll collect all urine for 24 hours, starting after you urinate in the morning. Store the urine in a refrigerator and return it to the lab on time. Avoid certain medications (like some steroids) that could affect results.

How the Test Works

Your urine is analyzed to detect cortisol levels at its highest point. Advanced lab techniques (likely immunoassay or chromatography) measure the concentration to determine if cortisol production is normal or abnormal.

Possible Results and Next Steps

Results may indicate whether cortisol production is too high or too low. Your doctor will interpret the peak value alongside other tests or symptoms to guide diagnosis or treatment adjustments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Cortisol Peak Testing

Short name

24-Hour Urine Cortisol Peak

Frequently asked questions

What does a high cortisol peak suggest?
A high peak may signal Cushing’s syndrome, excessive stress, or certain medications. It can also indicate overactive adrenal glands or pituitary issues that stimulate cortisol production.
What does a low cortisol peak suggest?
A low peak could point to adrenal insufficiency (e.g., Addison’s disease), where the body fails to produce enough cortisol. It may also occur with chronic stress or certain medications.
How often is this test repeated?
Your doctor may repeat this test if initial results are unclear or if symptoms persist. Follow-up may include additional hormone tests, imaging, or lifestyle adjustments to manage cortisol levels.
  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