Cortisol (Dexamethasone Suppression Test) With Reflex to Dexamethasone

TEST: 503990
Test number copied
CPT: 82533
Updated on 03/11/2025
Print Share

Synonyms

  • Dexamethasone Suppression Test

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 >1.7 μg/dL, dexamethasone test will be performed. Adequate dexamethasone drug level is confirmed with dexamethasone reflex measurement.

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.

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

TemperaturePeriod
Room temperature2 days
Refrigerated2 days
Frozen1 year
Freeze/thaw cyclesStable 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 >1.8 μg/dL after single-dose dexamethasone

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

Positive: Serum cortisol >1.8 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

For Providers

Please login to order a test

Order a Test

© 2025 Laboratory Corporation of America® Holdings. All Rights Reserved.

CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf