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Test Code CORTDS Dexamethasone Suppression Test, Overnight, Blood

Important Note

Low Dose Dexamethasone Suppression Test  (DST) protocol:   1 mg dexamethasone is taken orally at 11pm.   Then a serum cortisol is collected the following morning at 8 am.  


NOTE: The Dexamethasone must be provided to the patient by the ordering physician, either directly or via prescription.  

Additional Codes

Epic  LAB2767

Note: The LIS code CORTDS replaces DSTCOR on 4/16/19

Performing Laboratory

Bronson Laboratory Services-Chemistry

Reference Values

Post-dexamethasone suppression: <1.8 mcg/dL (a.m.) or 80% to 90% lower than basal cortisol value



Note: Concentration of cortisol in serum
attains adult values by the end of the first week of postnatal life
and thereafter does not vary with age.

Specimen Requirements

Specimen Type: Serum

Container/Tube: Serum gel

Specimen Volume: 5 mL

Specimen Minimum Volume: 0.5 mL serum

Collection Instructions:

1. Dexamethasone will be given by nursing service or physician
at 11 p.m.

2. Patient must fast after midnight.

3. At 8 a.m. the following day, submit a request form for
Cortisol, Plasma or Serum, and indicate “Dexamethasone
Suppression Test, Overnight, Blood.”

Specimen Transport Temperature


Test Classification and CPT Coding