|
What you need to know about Dexamethasone Suppression Tests
From The Pituitary Center at Vanderbilt
Dexamethasone suppression tests are employed by The Pituitary Center at Vanderbilt
in the evaluation of patients with
Cushing's syndrome.
Dexamethasone Suppression Tests
Dexamethasone suppression tests have been employed for more than 30 years in the evaluation of patients with
Cushing's syndrome. Several variations have been developed since Dr. Grant Liddle of Vanderbilt first reported on the usefulness of the classical test in 1960.
The adrenal glands produce cortisol, the major glucocorticoid hormone in man, in response to signals provided by the pituitary gland. Dexamethasone is a synthetic glucocorticoid hormone. In normal subjects, daily doses of Dexamethasone in excess of 0.5-0.75 mg, can suppress the coordinated functions of the hypothalamus,
pituitary and adrenal glands. Dexamethasone often fails to suppress the function of the hypothalamus,
pituitary, and adrenal glands in patients with Cushing's disease or syndrome. These observations form the basis for the Dexamethasone suppression tests.
 | Formal Low-Dose Dexamethasone Suppression Test
<
 |
This procedure is often employed in the diagnosis of Cushing's syndrome. Proper performance of the test requires precise timing and collection of urine samples as well as the ingestion of Dexamethasone at specified time intervals. Your physician may request that you collect several
"basal" 24-hour urine samples for determination
of free cortisol, 17-hydroxycorticosteroids, and creatinine. |
| The test begins on day one with the administration of the first of 8 doses
of Dexamethasone. You may be asked to take the first dose at 6:00
AM. If so, subsequent doses should be at 12:00 noon, 6:00 PM, and 12:00 midnight on day one and then 6:00 AM, 12:00 noon, 6:00 PM, and
12:00 midnight on day two. You may be asked to begin the medication
at some other time. If so, explicit guidelines will be provided to
ensure that you understand when to take the subsequent doses of the medication. |
| Most importantly, the medication should be taken every 6 hours for a total of 8 doses. |
| You should begin the 24-hour urine
collection at 6:00 AM on day two, coinciding with the 5th dose of the medication. |
| The urine
collection should be completed at 6:00 AM on day three. |
| Please review the instructions for 24-hour urine
collection.
Contact your physician if you have any questions. |
|
| | Dexamethasone-Suppressed CRH Stimulation Test
|
| |
Formal two day high dose Dexamethasone Suppression Test
|
This test is often employed in the differential diagnosis of Cushing's syndrome. It has largely been supplanted by the high dose 8 mg overnight Dexamethasone suppression test. |
|
|
Day 1
|
You
should begin a 24-hour urine
collection at 6:00 AM. |
|
Day 2
|
Finish
the first urine
collection at 6:00 AM and start the second 24-hour urine
collection. |
|
Day 3
|
Finish
the second 24-hour urine
collection at 6:00 AM and start the third
collection. Start Dexamethasone 0.5 mg at 6:00 AM and take subsequent
doses at 12:00 noon, 6:00 PM, and 12:00 midnight. |
|
Day 4
|
Finish
the third 24-hour urine
collection at 6:00 AM and start the fourth
collection. Continue Dexamethasone 0.5 mg at 6:00 AM, 12:00 noon,
6:00 PM, and 12:00 midnight. |
|
Day 5
|
Complete
the fourth 24-hour urine
collection at 6:00 AM and start the fifth
collection. Begin Dexamethasone 2.0 mg at 6:00 AM and take subsequent
doses at 12:00 noon, 6:00 PM, and 12:00 midnight. |
|
Day 6
|
Finish
the fifth 24-hour urine
collection at 6:00 AM and begin the sixth
collection. Continue Dexamethasone 2.0 mg at 6:00 AM, 12:00 noon,
6:00 PM, and 12:00 midnight. |
|
Day 7
|
Complete
the sixth 24-hour urine
collection at 6:00 AM. |
You
should ensure that all collection bottles are labeled with your name,
the start date of the collection, and as an extra precaution, indicate
the day of the collection (day 1, day 2, and so on). Transport the
specimens to the designated facility for testing.
Cushings-Help.com shall not be held liable for any claim or right to recover damages, including, but not limited to, loss of profit, business, other incidental consequential damages, or other similar claims, even if Cushings-Help.com has been specifically advised of the possibility of such damages.
| |
