A cortisol level test uses a blood sample to measure the level of cortisol present in blood. Cortisol is a steroid hormone released by the adrenal gland. The adrenal glands sit atop the kidneys. A cortisol level test may also be called a serum cortisol test.
Cortisol is a steroid hormone produced by the adrenal gland. It is released in response to ACTH (adrenocorticotropic hormone), which is produced by the pituitary gland near the brain. Adrenocorticotropic hormone stimulates the secretion of hormones by the adrenal cortex
Cortisol is the main hormone involved in stress and the “fight or flight” response. This response is a natural and protective response to a perceived threat or danger. A series of physiological responses cause cortisol and adrenal levels to increase, resulting in a burst of new energy and strength.
In the “fight or flight” response, cortisol acts to suppress any functions that are unnecessary or detrimental to the fight or flight response. Individuals can experience rapid heart rate, dry mouth, stomach upset, diarrhea and panic.
Cortisol release also suppresses growth processes, digestive and reproductive system functioning, and alters immune system responses.
The cortisol level test is done to check if cortisol production levels are either too high or too low. There are certain diseases, such as Addison’s disease and Cushing’s disease, which affect the amount of cortisol produced by the adrenal gland. The test is used in the diagnosis of these diseases and as a way to assess the functioning of the adrenal and pituitary glands.
Cortisol plays a role in several systems in the body. These systems include:
- stress responses
- immune system
- nervous system
- circulatory system
- metabolism of protein, fats, and carbohydrates
A blood sample is used to measure cortisol levels. A health professional usually follows these steps to collect the blood sample:
- The flow of blood in the arm is stopped by wrapping an elastic band around your upper arm. This also causes the veins in your arm to become more visible so the needle can be inserted easier.
- Alcohol is used to clean the site on your skin where the needle will be inserted.
- The needle is inserted into the vein. This may cause a brief pinching or stinging sensation.
- Blood is collected by attaching a tube to the needle. Sometimes more than one tube may be needed.
- The elastic band is removed after enough blood has been collected.
- As the needle is removed from the skin, cotton or gauze is place on the site of the injection.
- Pressure is applied to the area and bandage is used to secure the cotton or gauze.
There are few risks associated with the cortisol level test. The test is done by taking a blood sample from the vein, which may result in some bruising at the site where the needle was inserted.
In rare cases, the following risks may be associated with having blood drawn from a vein:
- excessive bleeding
- hematoma or the accumulation of blood beneath the skin
- light-headedness or fainting
Cortisol levels vary throughout the day. Your healthcare provider will usually request that the test is done in the morning.
There are certain drugs that affect cortisol levels, and your healthcare provider may request that you not take these drugs before the test is done. Cortisol levels are sometimes increased by:
- drugs containing estrogen
- synthetic glucocorticoids, such as prednisone
Cortisol levels are sometimes decreased by:
- drugs containing androgens
Cortisol levels can also be affected by physical stress, emotional stress, and illness. This is due to the increased release of ACTH by the pituitary gland during the normal stress response.
Normal results for a blood sample taken at 8 a.m. range between 6 and 23 micrograms per deciliter (mcg/dL). Normal values may vary between different laboratories due to different measuring techniques. The meaning of your test results should be discussed with your doctor.
Higher than normal cortisol levels may be sign of:
- Cushing’s disease, which causes the pituitary gland to release too much ACTH due to excess growth of the pituitary gland
- tumor of the adrenal gland, resulting in excess cortisol production
- tumor elsewhere in the body that is involved in cortisol production
Lower than normal cortisol levels may be a sign of:
- Addison’s disease, which occurs when production of cortisol by the adrenal glands is too low
- Hypopituitarism, which occurs when production of cortisol by the adrenal glands is too low because the pituitary gland is not sending proper signals.