Synonyms: Compound F; Hydrocortisone

Why It Is Done

*Problems of the pituitary gland or adrenal glands, such as producing too much or too little hormones.* Cushing's syndrome. A 24-hour urine sample is collected for this purpose.

Test Overview:

A cortisol test is done to measure the level of the hormone cortisol in the blood, which may indicate problems with the adrenal glands or pituitary gland. Cortisol is produced by the adrenal glands. Cortisol levels increase when the pituitary gland releases another hormone called adrenocorticotropic hormone (ACTH).
Cortisol has many functions. It helps the body break down food 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.
Two blood samples may be taken: one in the morning (AM) and another in the afternoon (PM). This test can also be done on a sample of urine collected over 24 hours (24-hour urine sample).

How to prepare

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 is done.
Be sure to drink enough fluids during the 24-hour urine test to prevent dehydration.