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Cortisol (Serum) with 24-Hour Urinary Free Cortisol Measurement

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

This test measures cortisol levels in your blood and collects a 24-hour urine sample to assess cortisol production over time.

Quick summary

["Cortisol helps regulate stress and metabolism; abnormal levels may indicate adrenal issues or hormone imbalances."]

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

Key facts at a glance

LOINC
26528-0
Short code
Cortis 1h p ACTH SerPl-mCnc
Synonyms
Cortis 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 Is Done

Your doctor may order this test to diagnose or monitor conditions like Cushing’s syndrome, Addison’s disease, or adrenal insufficiency. It also helps evaluate stress responses or hormone-related symptoms like fatigue, weight changes, or high blood pressure.

How the Test Works

A blood sample is drawn to measure cortisol immediately (serum) and a 24-hour urine collection is required to capture cortisol excreted over the full day. Both samples are analyzed to detect patterns in cortisol production.

What to Expect Before the Test

No special preparation is needed for the blood draw, but you may be asked to collect urine for 24 hours, starting after your first morning void. Follow your doctor’s instructions carefully to ensure accurate results.

What to Expect During the Test

The blood draw is quick and done in a lab setting. For the urine collection, you’ll need to collect all urine for 24 hours, discarding the first morning sample and combining all others. Store urine in a cool container if needed.

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

Frequently asked questions

What does a cortisol test measure?
It measures cortisol levels in your blood (immediately) and the total amount excreted in your urine over 24 hours. This helps assess whether your body produces cortisol at normal or abnormal levels.
Why is a 24-hour urine test needed?
A 24-hour urine test captures cortisol production throughout the day, as cortisol levels naturally fluctuate. This full-day measurement provides a more accurate picture of your body’s cortisol activity than a single blood sample.
Can I take medications before this test?
Yes, but inform your doctor about all medications, including over-the-counter drugs or supplements. Some medications may affect cortisol levels, so adjustments may be needed for accurate results.
  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