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Cortisol, Serum (Mass Concentration)

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

This test measures the amount of cortisol, a natural steroid hormone produced by your adrenal glands, in your blood serum. Cortisol helps regulate metabolism, immune response, and stress reactions.

Quick summary

["Cortisol levels can help diagnose adrenal gland disorders or stress-related conditions."]

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

Key facts at a glance

LOINC
50460-5
Short code
Cortis sp8 SerPl-mCnc
Synonyms
Cortis sp8 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 a cortisol test to check for conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or to evaluate how your body responds to stress or certain medications. It can also help assess adrenal gland function before surgery or during treatment for other health issues.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if timing cortisol levels around a specific time of day is important. If you’re taking medications that affect cortisol, your doctor will let you know if you should stop temporarily.

How the Test Is Done

A healthcare provider will draw blood from a vein in your arm. The blood sample is sent to a lab for analysis. Cortisol is measured in the serum portion of the blood.

What the Results Mean

Results are compared to reference ranges specific to the lab, which may vary. High or low cortisol levels can indicate underlying health concerns that require further evaluation by your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Cortisol

Frequently asked questions

What causes cortisol levels to be tested?
Cortisol tests are often ordered if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or unusual hair growth/thinning. They may also be part of a broader evaluation for chronic stress, sleep disorders, or suspected endocrine (hormone) disorders.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will contact you with the findings once they are ready.
Can I take anything before my cortisol test?
If fasting is required, avoid caffeine, alcohol, or heavy meals for the specified period. If your doctor has given specific instructions, follow them closely to ensure 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 16, 2026. · Read our editorial policy