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

Quick summary

["Cortisol helps manage stress and supports normal bodily functions, and this test helps assess adrenal gland health or hormone balance."]

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

Key facts at a glance

LOINC
50336-7
Short code
B-cortolone/Cortis Ur
Synonyms
B-cortolone/Cortis Ur
Category
hormone
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order cortisol tests to diagnose or monitor conditions like Cushing’s syndrome (excess cortisol), Addison’s disease (low cortisol), or adrenal insufficiency. It can also help evaluate symptoms such as fatigue, weight changes, or unusual mood swings that may relate to hormone imbalances.

What to Expect Before the Test

No special preparation is needed for a serum or plasma cortisol test. For a 24-hour urine test (if applicable), you may need to collect urine samples over a full day. If your doctor prescribes a specific timing (e.g., morning or evening), follow their instructions carefully.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch when the needle is inserted, but the procedure usually takes a few minutes. If a urine sample is collected, you’ll need to follow instructions to collect all urine over a set period.

What Do the Results Mean?

Results are interpreted based on your clinical symptoms, timing of the sample, and other tests. Abnormally high or low cortisol levels may indicate underlying health issues that require further evaluation by your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Cortisol levels are critical for managing stress responses, immune function, and metabolism. Abnormal results may signal conditions affecting the adrenal glands, pituitary gland, or other hormonal pathways. Your doctor will discuss findings in the context of your health history and symptoms to guide next steps.

Short name

Cortisol Level

Frequently asked questions

What causes cortisol levels to be too high?
High cortisol levels can result from conditions like Cushing’s syndrome (due to excess hormone production or medications), prolonged stress, or certain tumors affecting the adrenal glands or pituitary gland. Chronic conditions such as obesity or long-term steroid use may also contribute.
What causes cortisol levels to be too low?
Low cortisol levels, known as adrenal insufficiency, can stem from autoimmune diseases (e.g., Addison’s disease), infections, or damage to the adrenal glands. Rarely, it may occur after long-term steroid use or certain medications.
Can lifestyle changes affect cortisol levels?
Yes, lifestyle factors like sleep quality, stress management, diet, and exercise can influence cortisol levels. Poor sleep, chronic stress, or an unhealthy diet may temporarily elevate cortisol, while regular physical activity and stress reduction techniques may help balance them.
  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