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Test Name:
Dexamethasone, Serum or Plasma
- SBMF No:
43209 - Performance Lab Name:
Quest Diagnostics Nichols Institute - Test Mnemonic:
DEXAMETH - ABN:
Not required - CPT Code:
80299 - LOINC Code:
19146-0 - Ref Lab Test No:
29391X - Also Known As:
Dexamethasone Level - Also See:
30203 Dexamethasone Suppression Test, AM and PM Serum Cortisol Levels
30204 Dexamethasone Suppression Test, Low Dose, AM Serum Cortisol Level Only - Spec Type:
Serum - Spec Container:
Red top (serum) tube - Alt Spec Type:
Plasma - Alt Spec Container:
Green top (heparin) or gray top (fluoride/oxalate) tube - Pref Vol:
0.85 mL - Min Vol:
0.25 mL - Fasting:
No - Spec Collect:
Draw specimen between 8:00 and 10:00 A.M.
Do not use gel-barrier tubes for collection
Routine venipuncture - Spec Process:
Serum sample tubes, clot 30 minutes
Promptly centrifuge 15 minutes
Immediately transfer serum or plasma to separate plastic tube - Spec Store Transport:
Refrigerated - Spec Stability:
After separation from cells:
24 hours room temperature (20-30°C)
1 week refrigerated (2-8°C)
2 years frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Sample collected in gel-barrier tube
Sample received room temperature - Methodology:
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) - Clinical Significance:
Measurement of Dexamethasone is useful in assuring compliance with Dexamethasone treatment and documenting adequate dosing during such procedures as the Dexamethasone Suppression Test used in the differential diagnosis of Cushing's syndrome. - Reference Range:
- Dexamethasone, Serum or Plasma
- Baseline: Less than 20 ng/dL
1 mg Dexamethasone overnight: 180-550 ng/dL (8:00-10:00 a.m.)
- Day Run:
Varies; 1 run per week - Time Reported:
Reports in 2 days - Test Type:
TOX-TDM
