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Cortisol, Serum (Mass Concentration)

Published: August 9, 2026Updated: August 17, 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 levels help assess adrenal function and potential stress-related conditions."]

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

Key facts at a glance

LOINC
1417-5
Short code
Cortis 30M p 250 ug ACTH rIV SerPl-mCnc
Synonyms
Cortis 30M p 250 ug ACTH rIV 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 Is This Test Done?

Your doctor may order a cortisol test to diagnose or monitor conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or to check for adrenal gland issues. It can also help evaluate stress responses or hormone imbalances.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if timing cortisol levels around a specific time (e.g., morning peak) is important. Bring any medications you’re taking to your doctor’s office.

How the Test Is Performed

A blood sample is drawn from a vein in your arm by a healthcare professional. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is sent to a lab for analysis.

What the Results Mean

Results are compared to general reference ranges, but individual ranges can vary by lab. High cortisol levels may suggest overproduction (e.g., from tumors or stress), while low levels may indicate adrenal insufficiency. Your doctor will interpret results in the context of your symptoms and medical history.

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.

Cortisol levels are critical for diagnosing hormonal disorders, such as adrenal insufficiency (Addison’s disease) or hypercortisolism (Cushing’s syndrome). Abnormal results may also signal chronic stress, pituitary gland issues, or other endocrine problems. Follow-up testing may include additional cortisol measurements at different times (e.g., early morning vs. midnight) or other hormone tests.

Short name

Serum Cortisol

Frequently asked questions

Will I Need to Avoid Certain Foods or Drinks Before the Test?
If your test is timed (e.g., morning cortisol), avoid caffeine, alcohol, or heavy meals for 24 hours before. Otherwise, standard diet and hydration are fine unless instructed otherwise by your doctor.
Can Cortisol Levels Change Based on When the Test Is Taken?
Yes, cortisol naturally peaks in the early morning and drops at night. If your test isn’t timed, results may still be useful for general assessment, but timing can affect interpretation. Ask your doctor if timing is important for your specific situation.
What Are Common Causes of High or Low Cortisol Levels?
High cortisol can result from stress, certain medications, or conditions like Cushing’s syndrome. Low cortisol may stem from adrenal gland problems, autoimmune diseases, or long-term steroid use. Symptoms vary but can include fatigue, weight changes, or skin changes. Your doctor will guide further evaluation based on your 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