A cortisol test is done to measure the level
hormone cortisol in a 24-hour sample of urine. The
cortisol level may show problems with the
adrenal glands or the
pituitary gland. Cortisol is made by the
adrenal glands. Cortisol levels get higher when the
pituitary gland releases another hormone called
adrenocorticotropic hormone (ACTH).
Cortisol has many functions. It helps the body use sugar (glucose) and
fat for energy (metabolism), 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
Cortisol in urine is measured from all of the urine collected over 24 hours because of the wide variation in cortisol levels that occurs throughout the day.
Why It Is Done
cortisol test is done to find problems of the
pituitary gland or adrenal glands, such as making too much hormone, which
happens in Cushing's syndrome.
How To Prepare
You may be asked to avoid strenuous
physical activity the day before a cortisol test.
Be sure to
drink enough fluids during the 24-hour urine test to prevent
Many medicines may change the
results of this test. Be sure to tell your doctor about all the
nonprescription and prescription medicines you take.
Talk to your doctor about any concerns you have regarding the need
for the test, its risks, how it will be done, or what the results will mean. To
help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
24 hour urine
You start collecting your urine in the morning.
When you first get up, empty your bladder but do not save this urine. Write
down the time that you urinated to mark the beginning of your 24-hour
For the next 24 hours, collect all your urine.
Your doctor or lab will usually provide you with a large container that holds
about 1 gal (4 L). The
container has a small amount of preservative in it. Urinate into a small, clean
container and then pour the urine into the large container. Do not touch the
inside of the container with your fingers.
Keep the large container
in the refrigerator for the 24 hours.
Empty your bladder for the
final time at or just before the end of the 24-hour period. Add this urine to
the large container and record the time.
Do not get toilet paper,
pubic hair, stool (feces), menstrual blood, or other foreign matter in the
How It Feels
There is no pain while collecting a
24-hour urine sample.
There is no chance for problems while collecting
a 24-hour urine sample.
A cortisol test is done to measure the
level of the
hormone cortisol in a 24-hour sample of urine.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
One cause of Cushing's syndrome is
Cushing's disease, a condition caused by a
noncancerous tumor of the pituitary gland (adenoma). An adenoma causes the
pituitary gland to make too much of the hormone
adrenocorticotropic hormone (ACTH), which in turn
causes the adrenal glands to make too much cortisol.
ACTH can be
made by other conditions, such as cancer of the lung. This high ACTH level
causes the adrenal glands to make more cortisol.
The adrenal gland
can develop tumors (benign or cancerous) that make cortisol and cause Cushing's
A 24-hour urine test is used more often than a
cortisol blood test to diagnose Cushing's syndrome. To learn more about a cortisol blood test, see the topic
Cortisol in Blood.
Other tests that can
help determine if the pituitary gland or adrenal glands are working well
include the adrenocorticotropic hormone (ACTH) and dexamethasone suppression
tests. The ACTH stimulation test may be done when
Addison's disease is suspected.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
How this information was developed to help you make better health decisions.