 | | | | Medical Health Encyclopedia | |
Dexamethasone suppression test
| | | |
| |
| |
| Dexamethasone suppression test |
|
Definition:
Dexamethasone suppression test measures the response of the adrenal glands to ACTH. Dexamethasone is given and levels of cortisol are measured. Cortisol levels should decrease in response to the administration of dexamethasone. Alternative Names:
DST; ACTH suppression test; Cortisol suppression test Text Continues Below
How the test is performed:
There are two different types of dexamethasone suppression tests: the low-dose test and the high-dose test. Each type can either be done in an overnight or standard (3-day) way. For the low-dose overnight method, 1 mg of dexamethasone is given at 11 p.m., and the blood is drawn at 8 a.m. for a cortisol measurement (see venipuncture).
In the standard low-dose method, urine is collected at 24-hour intervals over 3 days for measurement of cortisol. On day 2, a low dose (0.5 mg) of dexamethasone is given by mouth every 6 hours for 48 hours. For the high-dose overnight method, a baseline cortisol is measured on the morning of the test, then 8 mg of dexamethasone is given at 11 p.m.. Blood is drawn at 8 a.m. for a cortisol measurement. For the standard high-dose test, urine is collected at 24-hour intervals over 3 days for measurement of cortisol. On day 2, a high dose (2 mg) of dexamethasone is given by mouth every 6 hours for 48 hours. How to prepare for the test:
The health care provider may advise you to discontinue drugs that may affect the test. Drugs that can affect test results include barbiturates, estrogens, corticosteroids, oral contraceptives, phenytoin, spironolactone, and tetracyclines. 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:
| 
.gif)
