A cortisol level is a blood test that measures the amount of cortisol, a steroid hormone produced by the adrenal cortex.
How the test is performed
Adult or child:
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. The tourniquet is then removed to restore circulation. After blood has been collected the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.
How to prepare for the test
The health care provider may advise you to discontinue drugs that can affect the test (see also “Special considerations”). Drugs that can increase cortisol measurements include estrogen and synthetic glucocorticoids, like prednisone and prednisolone. Drugs that can decrease cortisol measurements include androgens and phenytoin.
Infants and children:
The preparation you can provide for this test depends on your child’s age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- Schoolage test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
Cortisol levels are often measured to evaluate the pituitary and adrenal function.
Normal values at 8 a.m.are 6 to 23 mcg/dl. Normal value ranges may vary slightly among different laboratories.
Note: mcg/dl = micrograms per deciliter
What abnormal results mean
Greater than normal levels may indicate:
- Adrenal tumor
- Cushing’s syndrome
- Ectopic ACTH-producing tumors
Lower than normal levels may indicate:
- Addison’s disease
Additional conditions under which the test may be performed:
- Acute adrenal crisis
- Ectopic Cushing’s syndrome
- Pituitary Cushing’s (Cushing’s disease)
What the risks are
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
- Multiple punctures to locate veins
Cortisol is a steroid hormone released from the adrenal cortex in response to ACTH. Normally, cortisol levels rise and fall during the day, repeating on a 24-hour cycle (diurnal variation). Highest levels are at about 6 to 8 a.m. and lowest levels are at about midnight.
Physical and emotional stress can increase serum cortisol, because a normal response to stress involves increased secretion of ACTH by the pituitary gland.
by Martin A. Harms, M.D.