Dexamethasone (Blood)

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Testing Laboratory

Auckland Te Toka Tumai | Auckland Hospital

Department

Chemical Pathology

Delphic Registration Code (Alpha Code)

DEXT

Test Code (Numeric Code)

4115

Laboratory Handling

Transport

If sending within Auckland then sample can be sent refrigerated (2-8°C) or at ambient temperature (8-24°C).
If sending from outside Auckland then send sample refrigerated (2-8°C).

Registration

Internal samples: ADHB DEXA (post dexamethasone suppression test cortisol) samples should also be registered for DEXT. These samples can go onto the Cobas for Cortisol and then the aliquot put into the HPLC rack.
External samples: All other requests for Dexamethasone levels can just be registered for DEXT.

Separating

Centrifuge and separate blood as soon as possible after collection

Laboratory

LabPLUS High Performance Liquid Chromatography

Test Adds Requirement

Specimens requesting for " Cortisol - post Dexamethasone suppression test" will have a test add for dexamethasone level if the cortisol from the same specimen is >=50nmol/L. Specimens requesting for "Dexamethasone level" will have dexamethasone reported. Cortisol will not be reported unless specifically requested.

Sample Stability

In plasma/serum, at least 7 days at 4°C

Synonyms

Dexamethasone

Turnaround Time

1 week

TAT between 1 week and 2 weeks

Specimen Type

  • Plasma
  • Serum

Specimen Requirements

Tube/Container Type:

Preferred
  • Plain (Red Top)
Acceptable
  • Lithium Heparin - Non-gel (Green Cap)
  • Lithium Heparin PST- Gel (Light Green Cap)
  • SST II (Gold Cap)
Preferred Sample Volume (ml)

4

Paediatric Specimen Requirements

Tube/Container Type:

Preferred
  • Plain (Red Top)
Acceptable
  • Lithium Heparin - Non-gel (Green Cap)
  • Lithium Heparin PST- Gel (Light Green Cap)
  • SST II (Gold Cap)

Additional Specimen Information

Specimen Collection
I. ADHB samples:
a. If "Cortisol - post Dexamethasone suppression test" is requested, dexamethasone testing will be added only if the cortisol from the same specimen is >=50nmol/L.
b. If "Dexamethasone level" is requested, dexamethasone will be reported done regardless of cortisol level (but cortisol testing needs to be separately requested, if required).
II. Samples from outside LabPlus - Request "Dexamethasone level". Any cortisol test requested will be performed by the lab collecting the sample.

Last updated: 28/07/2026