Test Details
Methodology
High-pressure liquid chromatography (HPLC)/tandem mass spectrometry (MS-MS)
Result Turnaround Time
6 - 15 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Test Includes
If the cortisol (503990) result is >1.8 μg/dL, dexamethasone test will be performed. Adequate dexamethasone drug level is confirmed with dexamethasone reflex measurement.
If the cortisol (503990) result is >1. |
If the cortisol (503990) result is >1.8 μg/dL, dexamethasone test will be performed. Adequate dexamethasone drug level is confirmed with dexamethasone reflex measurement. |
Use
A reflex profile that tests adrenal suppression with dexamethasone.
Special Instructions
For more information regarding the administration and interpretation of the dexamethasone suppression test (DST) in the evaluation of patients for Cushing disease/syndrome, please see Dexamethasone Suppression Screening for Cushing Disease/Syndrome in the online Endocrine Appendix.
Limitations
False-positive results can be seen in obese individuals, in those who have had a poor night's sleep, and in individuals who are under acute emotional or physical stress.
References
Specimen Requirements
Specimen
Serum or plasma, frozen
Volume
3 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, or green-top (heparin) tube
Collection Instructions
Specimen must be separated from cells within one hour of venipuncture. Transfer serum or plasma to a plastic transport tube and freeze. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 2 days |
| Refrigerated | 2 days |
| Frozen | 1 year |
| Freeze/thaw cycles | Stable x3 |
Reference Range
Positive: Serum cortisol >1.8 μg/dL after single-dose dexamethasone
Positive: Serum cortisol >1. |
Positive: Serum cortisol >1.8 μg/dL after single-dose dexamethasone |
Storage Instructions
Freeze.
Causes for Rejection
Gross hemolysis
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 503990 | Cortisol Dexamethasone Reflex | 505957 | Cortisol, Serum LCMS | ug/dL | 2143-6 | |
| 503990 | Cortisol Dexamethasone Reflex | 503991 | Dexamethasone Reflex | N/A | ||
| Order Code | 503990 | |||||
| Order Code Name | Cortisol Dexamethasone Reflex | |||||
| Order Loinc | ||||||
| Result Code | 505957 | |||||
| Result Code Name | Cortisol, Serum LCMS | |||||
| UofM | ug/dL | |||||
| Result LOINC | 2143-6 | |||||
| Order Code | 503990 | |||||
| Order Code Name | Cortisol Dexamethasone Reflex | |||||
| Order Loinc | ||||||
| Result Code | 503991 | |||||
| Result Code Name | Dexamethasone Reflex | |||||
| UofM | ||||||
| Result LOINC | N/A |
| Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
|---|---|---|---|---|---|---|
| Reflex 1 | 500118 | Dexamethasone, Serum | 500119 | Dexamethasone, Serum | ng/dL | 14062-4 |
| Reflex 1 | ||||||
| Order Code | 500118 | |||||
| Order Name | Dexamethasone, Serum | |||||
| Result Code | 500119 | |||||
| Result Name | Dexamethasone, Serum | |||||
| UofM | ng/dL | |||||
| Result LOINC | 14062-4 | |||||
| Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
|---|---|---|---|---|---|---|
| Reflex 1 | 500118 | Dexamethasone, Serum | 500980 | Dexamethasone, Serum | N/A | |
| Reflex 1 | ||||||
| Order Code | 500118 | |||||
| Order Name | Dexamethasone, Serum | |||||
| Result Code | 500980 | |||||
| Result Name | Dexamethasone, Serum | |||||
| UofM | ||||||
| Result LOINC | N/A | |||||