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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.

Quick summary

["Cortisol helps regulate metabolism, immune response, and stress reactions."]

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

Key facts at a glance

LOINC
50456-3
Short code
Cortis sp4 SerPl-mCnc
Synonyms
Cortis sp4 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 Is This Test Done?

Your doctor may order a serum cortisol test to check for conditions like Cushing’s syndrome (overactive adrenal glands), adrenal insufficiency (underactive adrenal glands), or to evaluate stress-related hormone levels. It can also help diagnose problems with the pituitary gland or adrenal glands, which control cortisol production.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is processed to separate serum (the liquid part after clotting) for analysis. The test measures cortisol’s mass concentration in this serum.

What Are Common Uses?

Serum cortisol testing is often used in combination with other tests (like ACTH stimulation tests) to diagnose hormonal imbalances. It may also be part of routine monitoring for known adrenal or pituitary disorders.

What to Expect Before the Test

No special preparation is usually needed, but if your doctor suggests timing (e.g., morning samples for cortisol), follow their instructions. Avoid caffeine or stress before the draw if advised.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum Cortisol

Frequently asked questions

Cortisol levels can rise with stress, illness, or certain medications. Low levels may indicate adrenal failure, while high levels could signal overproduction (e.g., from tumors or excess steroid use). Chronic stress or medical conditions like diabetes can also affect cortisol.
A serum cortisol test alone may not provide a full picture. Your doctor might compare results with other tests (like ACTH or 24-hour urine cortisol) for accurate diagnosis.
How accurate is this test?
This test is generally reliable, but results can be influenced by timing (e.g., morning vs. evening samples) or recent stress or medications. Always discuss your results with your healthcare provider.
Can I eat or drink before this test?
Typically, you can eat and drink normally unless your doctor specifies otherwise. Some tests may require fasting, but cortisol testing usually does not.
  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