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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
58655-2
Short code
Cortis 2 PM SerPl-mCnc
Synonyms
Cortis 2 PM 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), Addison’s disease (underactive adrenal glands), or to evaluate stress responses, especially if you have symptoms like unexplained weight changes, fatigue, or high blood pressure.

What to Expect Before the Test

No special preparation is needed, but if your doctor suggests timing (e.g., early morning for peak levels), follow their instructions. You’ll typically have blood drawn from a vein in your arm, similar to other blood tests.

What the Results Mean

Results help determine whether your cortisol levels are too high or too low. Abnormal levels may indicate hormonal imbalances or other health issues that need further medical evaluation.

Common Conditions Linked to Cortisol Testing

High cortisol levels might be linked to conditions like Cushing’s syndrome, chronic stress, or certain tumors. Low cortisol levels could suggest Addison’s disease, autoimmune disorders, or severe infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Cortisol

Frequently asked questions

How is cortisol measured in this test?
This test uses a blood sample to measure cortisol’s mass concentration, typically analyzed via immunoassay (a method detecting hormone presence). The method detects cortisol’s chemical structure without specifying exact numeric ranges.
What if my cortisol levels are out of range?
If results are abnormal, your doctor may recommend further testing (e.g., 24-hour urine cortisol or ACTH stimulation tests) or additional bloodwork to pinpoint the cause. Treatment depends on the underlying condition, such as medication or lifestyle adjustments.
Can cortisol levels change based on time of day?
Yes, cortisol naturally peaks in the morning and declines later. If your test isn’t timed correctly, results may not reflect typical daily fluctuations. Always follow your doctor’s instructions for optimal testing.
  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