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Test Code CORDST Cortisol DST

Additional Codes

 Test ID
CORDST

EPIC Test ID
LAB2383

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements

Container/Tube:

Preferred: Green-top (heparin) tube

Acceptable: Gold-top serum gel tube or Plain Red-top tube, lavender EDTA plasma
Specimen Volume: 170 uL of plasma or serum

Stability: Due to possible evaporation effects, samples and calibrators on the analyzers should be analyzed/measured within 2 hours. Stable for 24 hours at 20‑25 °C, 4 days at 2‑8 °C, 12 months at ‑20 °C (± 5 °C). Freeze only once.

Collection Instructions: Dexamethasone is given orally at 2300 or 2400 hours. Blood for a cortisol determination is drawn at 0800 the following morning.

Note: 1. Nursing unit must order dexamethasone from pharmacy (with dosage to be determined by physician).

 

Reference Values

Cortisol: ≤3.0 ug/dL (post administration of 1 mg dose)

Cortisol: <50% of baseline (post administration of 4 mg dose)

Day(s) Test Set Up

Monday through Sunday

Useful For

The dexamethasone Suppression Test is helpful in aiding in the diagnosis of Cushing's Syndrome.

Methodology

Chemiluminescent/Competitive Binding Immunoenzymatic Assay

Test Classification and CPT Coding

82533

Report Available

STAT:  Within 1 hour of receipt

Routine:  Within 2 hours of receipt