Cortisol (Dexamethasone Suppression Test) With Reflex to Dexamethasone

TEST: 503990
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CPT: 82533
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Synonyms

  • Dexamethasone Suppression Test

Test Includes

If the cortisol (503990) result is >1.7 μg/dL, dexamethasone test will be performed. Adequate dexamethasone drug level is confirmed with dexamethasone reflex measurement.

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.

Expected 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.

Related Information

Related Documents

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

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.

Storage Instructions

Freeze.

Stability Requirements

Temperature

Period

Room temperature

2 days

Refrigerated

2 days

Frozen

1 year

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross hemolysis

Test Details

Use

A reflex profile that tests adrenal suppression with dexamethasone.

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.

Methodology

High-pressure liquid chromatography (HPLC)/tandem mass spectrometry (MS-MS)

Reference Interval

Positive: Serum cortisol >1.7 μg/dL after single-dose dexamethasone

References

Magiakou MA, Mastorakos G, Oldfield EH, et al. Cushing's syndrome in children and adolescents. Presentation, diagnosis, and therapy. N Engl J Med. 1994 Sep 8; 331(10):629-636. 8052272

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
Reflex Table for Dexamethasone Reflex
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 500118 Dexamethasone, Serum 500119 Dexamethasone, Serum ng/dL 14062-4
Reflex Table for Dexamethasone Reflex
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 500118 Dexamethasone, Serum 500980 Dexamethasone, Serum N/A

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