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HelpTest Code LAB4061 DEXAMETHASONE SUPPRESSION TEST
Specimen Type
Preferred Sample: Lithium Heparin Plasma (PST, Mint Green Tube)
Alternate Sample: Serum (SST, Gold, Corvac, Tiger, Red Top Tube), Lithium Heparin (Dark Green top tube)
Specimen Volume
1 mL for each timed sample
Minimum Volume
0.5 mL for each timed sample
Turnaround Time
STAT: 1 hour
Routine: 4 hours
Times are after each specimen is drawn
Test Schedule
Daily
Sample Stability
Refrigerated: 14 days
Frozen: 30 days
Method
Chemiluminescent microparticle immunoassay (CMIA)
Reference Ranges
Cortisol Pre-Suppression ug/dL
AM: 3.7-19.4 ug/dL
Random: 2.9-17.3 ug/dL
Cortisol Post-Suppression ug/dL
Normal patients suppress their cortisol levels to LT 5.0 ug/dL
Reporting Limit
Reporting Range: 1.0 -119.6 ug/dL
Synonyms
Cortisol Suppression (2 samples)
CPT Codes
82533 × 2
Test Components
Cortisol Pre-Suppression, ug/dL; Date/Time Collected; Cortisol Post-Suppression, ug/dL; Date/Time Collected.
Specimen Processing
Spin completely clotted SST tube for 10 minutes. Store tubes in refrigerator until testing can be done.
Collection Instructions
Low Dose: Draw cortisols at 8:00 am the morning before and the morning after an 11:00 pm oral dose of 1.0 mg dexamethasone.
High Dose: Draw cortisols at 8:00 am the morning before and the morning after an 11:00 pm oral dose of 8.0 mg dexamethasone.
See also: Cortisol Collection Job Aid in PPM
Notes
Low dose dexamethasone usually does not suppress cortisol production in Cushing's Syndrome.