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24-Hour Urinary Free Cortisol

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

This test measures how much cortisol your body excretes in urine over a full day. It helps assess adrenal gland function and detect conditions like Cushing’s syndrome or adrenal insufficiency.

Quick summary

["Evaluates long-term cortisol levels to diagnose hormonal imbalances."]

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

Key facts at a glance

LOINC
24395-6
Short code
Cortis 24h p 1 mg Dex SerPl-sCnc
Synonyms
Cortis 24h p 1 mg Dex SerPl-sCnc
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 hormonal issues, such as an overactive or underactive adrenal gland, or to check for conditions like Cushing’s syndrome (excess cortisol) or Addison’s disease (low cortisol). It’s also used in research or monitoring certain treatments.

What to Expect Before the Test

You’ll collect all your urine for a full 24-hour period, typically starting and ending at the same time each day. Store the urine in a refrigerator or at room temperature, and keep a record of when you urinate. Follow any specific instructions your lab provides.

How the Test Works

The collected urine is analyzed to measure cortisol levels, which are then compared to expected ranges to identify any abnormalities.

What the Results Mean

High cortisol levels may indicate conditions like Cushing’s syndrome, while low levels could suggest adrenal insufficiency or other hormonal disorders. Your doctor will interpret results in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing and managing conditions related to cortisol production. Elevated cortisol can cause weight gain, fatigue, or high blood pressure, while low cortisol may lead to weakness, dizziness, or low blood pressure. It helps guide treatment plans for adrenal disorders or other hormonal imbalances.

Short name

24h Urine Cortisol

Frequently asked questions

How is the test collected?
You’ll need to collect every bit of urine for 24 hours, starting and ending at the same time each day. Some labs may provide a special container to keep the urine cold, so follow their instructions carefully.
Will I need to change my diet or activity level before the test?
Generally, no special diet is required, but avoid taking certain medications (like some steroids) that could affect cortisol levels without approval from your doctor. Activity levels don’t typically impact the test.
What if I miss any urine during the 24-hour period?
If you miss urine, you’ll need to restart the collection at the next scheduled time. Some labs may allow partial collection if circumstances prevent full completion, but this should be discussed with your healthcare provider beforehand.
  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