Cortisol, Serum or Plasma, Substance Concentration
This test measures the amount of cortisol, a 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; levels can indicate health or medical conditions."]
Key facts at a glance
- LOINC
- 44917-3
- Short code
- Cortis p Dex SerPl-sCnc
- Synonyms
- Cortis p Dex 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 Is This Test Done?
Your doctor may order cortisol testing to diagnose or monitor conditions like adrenal gland disorders (such as Cushing’s syndrome or Addison’s disease), evaluate stress responses, or check for hormonal imbalances. It can also help assess pituitary function or rule out other causes of symptoms like fatigue, weight changes, or high blood pressure.
What to Expect Before the Test
No special preparation is usually needed, but if your doctor instructs you to avoid certain medications or activities (like caffeine or stress), follow their advice. For plasma tests, you may need to fast for a short period, while serum tests can often be done after eating. Blood is drawn from a vein, typically in your arm, and you may feel a slight pinch.
What the Results Mean
Cortisol levels vary throughout the day, peaking in the morning and dropping at night. Your results will be compared to standard ranges for your age and health status. Abnormally high or low levels may signal underlying medical conditions that require further evaluation.
Common Conditions Linked to Cortisol Testing
High cortisol levels may be linked to conditions like Cushing’s syndrome (caused by excess cortisol production), certain tumors, or prolonged stress. Low cortisol levels can indicate Addison’s disease (adrenal insufficiency), pituitary disorders, or autoimmune conditions. Your doctor will interpret results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cortisol testing is critical for diagnosing adrenal or pituitary disorders, stress-related conditions, and evaluating hormonal imbalances. It helps guide treatment plans for managing chronic illnesses or managing acute symptoms like fatigue or weight changes.
Short name
Cortisol Level
Frequently asked questions
What does a cortisol test measure?
How is cortisol tested?
Can cortisol levels change based on time of day?
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