Test Overview
A cortisol test is done to measure the level of the
hormone cortisol in the blood. The cortisol level may show problems with the
adrenal glands or
pituitary gland. Cortisol is made by the
adrenal
glands
. Cortisol levels go up 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.
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. However, 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 called
Cushing's syndrome.
Two blood samples may be taken: one in the morning and another in
the afternoon.