Cortisol, Serum or Plasma, Mass Concentration
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 helps assess adrenal gland health or hormone imbalances."]
Key facts at a glance
- LOINC
- 35202-1
- Short code
- Cortis SerPl-msCnc
- Synonyms
- Cortis SerPl-msCnc
- 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 healthcare provider may order this test to diagnose or monitor conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or adrenal insufficiency. It can also help evaluate stress responses, hormone imbalances, or symptoms like fatigue, weight changes, or high blood pressure.
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 it involves a morning sample. If you’re taking medications that affect cortisol levels, let your provider know.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm. The sample is sent to a lab for analysis using a sensitive method to measure cortisol concentration.
What Are Possible Results?
Results are compared to general reference ranges for cortisol levels in serum or plasma. Abnormal results may indicate conditions affecting adrenal function or stress responses.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cortisol plays a key role in managing stress, immune function, and metabolism. High cortisol levels (e.g., from chronic stress or Cushing’s syndrome) may cause weight gain, high blood pressure, or muscle weakness. Low cortisol levels (e.g., Addison’s disease) can lead to fatigue, dizziness, or low blood pressure. Your provider will interpret results in the context of your symptoms and medical history.
Short name
Cortisol Level
Frequently asked questions
What does a high cortisol level mean?
What does a low cortisol level mean?
Can diet or medications affect cortisol levels?
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