Skip to content

Cortisol (Serum) – 24-Hour Urinary Free Cortisol

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

This test measures the amount of cortisol, a natural steroid hormone, excreted in your urine over a full day. It helps assess how well your body produces and regulates cortisol levels.

Quick summary

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

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

Key facts at a glance

LOINC
24390-7
Short code
Cortis 30M p 250 ug ACTH IM SerPl-sCnc
Synonyms
Cortis 30M p 250 ug ACTH IM SerPl-sCnc
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 Is Done

Your doctor may order this test if they suspect conditions like Cushing’s syndrome (too much cortisol) or adrenal gland issues (too little cortisol). It can also help monitor treatment for these conditions or check for hormonal imbalances.

How the Test Works

You’ll collect all urine for a 24-hour period, typically starting and ending at the same time each day. The urine is then sent to the lab for analysis to measure cortisol levels.

Sample Collection Process

To prepare, keep track of your urine output in a container every hour. Store the collected urine in a refrigerator until you return it to the lab. Do not miss any urine—this ensures an accurate measurement of your daily cortisol levels.

What to Expect Before the Test

No special preparation is needed, but avoid taking any medications that might affect cortisol levels (like some steroids) without consulting your doctor. Stress or illness can also temporarily alter results, so inform your doctor if you have recent changes in health.

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.

◆Associated findings1

Short name

24-Hour Urine Cortisol

Frequently asked questions

What does a high cortisol level mean?
High cortisol levels may indicate conditions like Cushing’s syndrome, where the body produces too much cortisol due to a tumor or prolonged steroid use. Repeatedly high levels can lead to weight gain, high blood pressure, and weakened bones.
What does a low cortisol level mean?
Low cortisol levels may suggest adrenal insufficiency, where the adrenal glands don’t produce enough cortisol. This can cause fatigue, low blood pressure, and increased susceptibility to infections.
Could stress affect this test?
Yes, stress can temporarily raise cortisol levels. If you’re under significant stress or have recent illness, your doctor may need to adjust interpretation or retest later.
  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