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HelpEpic Test Code LAB3766 Warfarin, Plasma
Additional Codes
MML:FWARP
Specimen Required
**Must submit one specimen per order. Specimens cannot be shared between multiple orders.***
Collection Container/Tube: EDTA (lavender top) or pink top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Draw blood in EDTA (lavender top) or pink top tube(s). Plasma gel tube is not acceptable.
2. Centrifuge and send 1 mL of plasma refrigerate in preservative-free plastic vial.
Method Name
High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Reporting Name
Warfarin, PlasmaSpecimen Type
Plasma EDTASpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma EDTA | Refrigerated (preferred) | 30 days | |
| Ambient | 30 days | ||
| Frozen | |||
Reject Due To
| Other | Polymer gel separation tube (SST or PST) |
Reference Values
Reporting limit determined each analysis.
None Detected mcg/mL
Day(s) Performed
Monday-Sunday
Report Available
9 to 11 daysSpecimen Retention Time
2 weeksPerforming Laboratory
NMS LabsCPT Code Information
80375
NY State Approved
YesInterpretation
The dosage of warfarin is best adjusted based on the International Normalized Ratio (INR) for prothrombin time. Peak plasma concentrations following single 10 mL doses averaged 0.6 mcg/mL for both R-warfarin and S-warfarin (combined concentration 1.2 mcg/mL). This test is not chiral specific and does not distinguish between the R and S enantiomers of warfarin. The blood to plasma ratio is approximately 0.5.