Tests of adrenal reserve
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Alternative names
ACTH (Cortrosyn) stimulation test
Definition
ACTH (Cortrosyn) stimulation test measures the ability of the adrenal cortex to respond to ACTH by producing cortisol appropriately. ACTH is a hormone produced in the pituitary gland that stimulates the adrenal glands.
How the test is performed
Blood measurements of cortisol are obtained—1 before and 1 or more after injection of ACTH.
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.
Once the blood has been collected, a needle is used to inject Cortrosyn, and additional timed specimens are collected.
Along with the blood tests, sometimes a urinary free cortisol test or urinary 17-ketosteroids may also be measured. The urine is collected over a 24-hour period.
How to prepare for the test
You may need to limit activities and eat a high-carbohydrate diet 12 to 24 hours before the test. You may be asked to fast for 6 hours before the test.
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)
- School age 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
This test is helpful in determining if the adrenal and pituitary glands are normal. It is most often used when adrenal gland disorders, such as Addison’s disease or pituitary insufficiency, are suspected.
Normal Values
An increase in cortisol after stimulation by ACTH is normal. Post-stimulation blood cortisol should be greater than 20 mcg/dl.
Normal value ranges may vary slightly among different laboratories.
Note: mcg/dl = micrograms per deciliter
What abnormal results mean
This test is helpful in determining if you have:
- Addison’s disease (decreased adrenal output)
- Low pituitary function
- Pituitary tumors
- Acute adrenal crisis
What the risks are
From venipuncture:
- 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
Special considerations
There are none.
by Levon Ter-Petrosyan, D.M.D.
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