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Cortisol, Serum or Plasma, 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. Cortisol helps regulate metabolism, immune response, and stress reactions.

Quick summary

["Cortisol helps manage stress and supports normal bodily functions."]

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

Key facts at a glance

LOINC
12570-8
Short code
Cortis p chal SerPl-mCnc
Synonyms
Cortis p chal 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 cortisol testing to check for conditions like adrenal gland issues (such as Cushing’s syndrome or Addison’s disease), evaluate stress responses, or monitor hormone imbalances. It can also help diagnose problems with the pituitary gland or adrenal glands, which control hormone production.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where cortisol levels are measured using a specialized method, often an immunoassay. Results help determine if your hormone levels are too high or too low.

What Are Common Uses?

Cortisol testing is commonly used to diagnose hormonal disorders, assess adrenal function, or evaluate symptoms like fatigue, weight changes, or unusual mood swings that may be linked to hormone imbalances.

What Might Affect Results?

Several factors can influence cortisol levels, including time of day (cortisol peaks in the morning), stress, certain medications (like steroids), or recent physical activity. If you’re taking medications or have conditions like depression or sleep disorders, let your doctor know.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cortisol Level

Frequently asked questions

How is cortisol testing different from other hormone tests?
Cortisol testing specifically measures cortisol in your blood or plasma, unlike some other hormone tests that may use saliva or urine samples. The method used (often immunoassay) detects cortisol molecules directly in your bloodstream.
What should I do if my cortisol test results are abnormal?
If your results are outside the expected range, your doctor may recommend further testing, such as a 24-hour urine cortisol test or a dexamethasone suppression test, to get a clearer picture of your adrenal function. Follow-up may also include additional bloodwork or imaging.
Can cortisol levels change based on when the test is taken?
Yes, cortisol levels naturally rise and fall throughout the day, with the highest levels typically occurring in the morning. If your test is for diagnostic purposes, timing matters—some tests may require blood drawn early in the morning for accuracy.
  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