Cortisol & Adrenal Tests
Answers to common questions about cortisol & adrenal tests.
Questions on this page
What is cortisol?
Cortisol is an adrenal hormone that helps regulate metabolism, blood pressure and the body's response to stress.
What is an 8 AM cortisol?
Cortisol normally follows a daily rhythm and is usually higher in the morning.
An early-morning cortisol measurement can be useful when adrenal insufficiency is suspected.
Can one cortisol value diagnose Cushing syndrome?
Usually not.
Evaluation for cortisol excess often requires specialized tests such as:
- Overnight dexamethasone suppression testing
- 24-hour urinary free cortisol
- Late-night salivary cortisol
What is ACTH?
ACTH is produced by the pituitary gland and stimulates the adrenal glands to produce cortisol.
Why are cortisol tests sometimes difficult to interpret?
Cortisol levels can be influenced by:
- Time of day
- Stress
- Acute illness
- Sleep pattern
- Medications
- Hormonal conditions