Cortisol in Blood Test
Test Overview
A cortisol test is done to measure the level of the hormone, Opens dialog cortisol in the blood. The cortisol level may show problems with the adrenal glands, Opens dialog or pituitary gland, Opens dialog. Cortisol is made by the adrenal glands, Opens dialog. Cortisol levels go up when the pituitary gland, Opens dialog releases another hormone called adrenocorticotropic hormone, Opens dialog (ACTH).
Cortisol has many functions. It helps the body use sugar (glucose) and fat for energy (metabolism, Opens dialog), and it helps the body manage stress. Cortisol levels can be affected by many conditions, such as physical or emotional stress, strenuous activity, infection, or injury.
Normally, cortisol levels rise during the early morning hours and are highest about 7 a.m. They drop very low in the evening and during the early phase of sleep. But if you sleep during the day and are up at night, this pattern may be reversed. If you do not have this daily change (diurnal rhythm) in cortisol levels, you may have overactive adrenal glands. This condition is called Cushing's syndrome, Opens dialog.
The timing of the cortisol test is very important because of the way cortisol levels vary throughout a day. If your doctor thinks you might make too much cortisol, the test will probably be done late in the day. If your doctor thinks you may not be making enough, a test is usually done in the morning.
A cortisol, Opens dialog test is done to find problems of the pituitary gland or adrenal glands, such as making too much or too little hormones.
You may be asked to avoid strenuous physical activity the day before a cortisol test. You may also be asked to lie down and relax for 30 minutes before the blood test.
Some medicines, such as steroids, can affect cortisol levels for some time even after you stop taking the medicine.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Normal
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
High values
- A high level of cortisol in the blood can mean Cushing's syndrome, Opens dialog, a disorder that can be caused by overactive adrenal glands, an adrenal gland tumor, some types of cancer, or long-term use of corticosteroids, Opens dialog.
- A high blood cortisol level can be caused by severe liver or kidney disease, depression, Opens dialog, hyperthyroidism, Opens dialog, or obesity, Opens dialog.
- Pregnancy or birth control pills can also cause a high blood cortisol level.
- Conditions such as recent surgery, illness, injury, or whole-body infection (sepsis) can cause high cortisol levels.
Low values
- A low level of cortisol in the blood can be caused by:
- Problems that affect the adrenal glands directly, such as Addison's disease, Opens dialog or a tuberculosis infection of the adrenal glands.
- Problems with the pituitary gland, Opens dialog that affect the adrenal glands, such as cancer or a head injury.
Current as of: April 30, 2024
Author: Ignite Healthwise, LLC Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
Current as of: April 30, 2024
Author: Ignite Healthwise, LLC Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
This information does not replace the advice of a doctor. Ignite Healthwise, LLC, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.