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.
How It Is Done
This test is usually done at home. You must collect all the urine you produce in a 24-hour period.
When you first get up in the morning, urinate into the toilet. Don't save this urine. This marks the start of your 24-hour period.
For the next 24 hours, collect all your urine. Your doctor or lab will give you a large container to store it in. Urinate into a separate small, clean container. Then pour the urine into the large container. Don't touch the inside of the containers with your fingers.
Keep the large container in the refrigerator.
Empty your bladder for the last time at or just before the end of the 24-hour period. Add this urine to the large container, and write down the time.
Do not get toilet paper, pubic hair, stool (feces), menstrual blood, or anything else in your urine sample.
How It Feels
This test usually doesn't cause any pain or discomfort.
There are no known risks from having this test.
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 of cortisol may be caused by:
Pituitary and adrenal tumours, which are usually benign. This means they are not cancer.
Some types of cancer, such as adrenal cancer and some rare lung cancers.
Medical Review:E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Alan C. Dalkin MD - Endocrinology
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