| Subject | Contents |
| Definition | A test to measure 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 . |
| Alternative Names | Tests of adrenal reserve |
| 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 ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the 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. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. Once the blood has been collected, a needle is used to inject Cortrosyn, and additional timed specimen(s) are collected. Along with the blood tests, sometimes a urinary free cortisol test and/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 physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age: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 | 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. 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 functionpituitary tumorsacute adrenal crisis |
| What the risks are | From venipuncture : excessive bleedingfainting 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 | |
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