Cortisol (Substance Concentration) in Serum or Plasma
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.
["Cortisol helps manage stress and supports normal bodily functions, and this test checks your blood levels for medical evaluation."]
Key facts at a glance
- LOINC
- 58656-0
- Short code
- Cortis 2 PM SerPl-sCnc
- Synonyms
- Cortis 2 PM SerPl-sCnc
- 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 Might You Need This Test?
Your healthcare provider may order cortisol testing to diagnose or monitor conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or adrenal gland issues. It can also help assess stress responses, hormone imbalances, or evaluate symptoms like fatigue, weight changes, or unusual moods.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if timing your cortisol levels around certain times of day (morning or evening) is important. Bring any medications you’re taking to your appointment.
How the Test Works
A blood sample is drawn from a vein in your arm. The sample is then sent to a lab to measure cortisol concentration using a sensitive immunoassay method, which detects the hormone’s presence in your blood.
What the Results Mean
Results are compared to reference ranges specific to your age, sex, and health status. Abnormally high or low cortisol levels may signal underlying medical conditions that require further evaluation, such as hormone testing or imaging studies.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Cortisol Level
Frequently asked questions
Cortisol levels can fluctuate throughout the day, peaking in the morning and dropping at night. Abnormal patterns may indicate adrenal dysfunction, pituitary disorders, or chronic stress. Persistent high cortisol can lead to weight gain, high blood pressure, or weakened immunity, while low cortisol may cause dizziness, fatigue, or muscle weakness.
This test measures the amount of cortisol (a stress hormone) in your blood, helping diagnose conditions related to adrenal gland function or hormone imbalances.
Generally, no fasting is required unless your provider specifies timing for specific cortisol measurements (e.g., morning vs. evening). Always follow your healthcare provider’s instructions.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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