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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
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
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.
Notes
Low dose dexamethasone usually does not suppress cortisol production in Cushing's Syndrome.