Published on July 16, 2024

Low Dose Dexamethasone Suppression Testing-Cortisol 

Tube type

LAB17021
EPIC ORDER LOW DOSE DEXAMETHASONE SUPPRESSION TESTING-CORTISOL
CPT Code(s) 82533
Group/Individual Test Individual 
Laboratory Core Laboratory
Tube Station Routine: 30, STAT: 888 
Specimen Routine: 4 mL blood/green lithium heparin gel tube. Also acceptable gold SST or red plain tube. See Comments for additional specimen information.
Micro: 0.9 mL blood/mint green top bullet/gold top/red top
Stability Unspun: <8 hours
Spun/Separated: Room Temperature: 8 hours
Refrigerated:  2 days
Frozen:  4 weeks
Availability Routine: 24 hrs/day
STAT: Yes
Turnaround Time Routine: 2 hrs; STAT: 1 hr
Reference Range Normal: < 1.8 mcg/dL
Critical Values NONE
Comments
  • This test is intended to rule out Cushing syndrome (CS) in patients with suspected hyper cortisol states after overnight 1mg dexamethasone administration. Serum cortisol levels under 1.8 mcg/dL suggest adequate HPA axis suppression by dexamethasone to exclude CS. Levels greater than 1.8 mcg/dL should be verified with a second test (24-hour urinary free cortisol and/or late-night salivary cortisol) before establishing a confirmed diagnosis. 
  • This test is performed using the Siemens Atellica IM Cortisol assay. Different test methods should not be used interchangeably. Heterophilic antibodies may cause interference. 

Reviewed by J. Carr on December 31, 2025

UNC Hospitals
McLendon Clinical Laboratories
101 Manning Drive
Chapel Hill, NC 27514