Cortisol in Urine
A cortisol test measures the level of the 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 adrenocorticotropic hormone (ACTH).
Cortisol has many functions. It helps the body use sugar (glucose) and fat for energy (metabolism). It helps the body manage stress. Cortisol levels can be affected by many things, 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 in cortisol levels, you may have overactive adrenal glands.
Cortisol levels vary widely throughout the day, so you collect urine over 24 hours for this test.
Why It Is Done
A cortisol test is done to find problems of the pituitary gland or adrenal glands, such as making too much hormone.
How To Prepare
You may be asked to avoid strenuous physical activity the day before the test.
Be sure to drink enough fluids during the 24-hour urine test. This prevents dehydration.
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?).