Warfarin Drug Level
Label Mnemonic: WARF
Epic Lab Code: LAB4274
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Collection Medium:
and
Red top tube 5 mL (Clot Activator) Red top tube 5 mL (Clot Activator)
Minimum:
Preferred Minimum: 3 mL serum
Absolute Minimum: 1.1 mL serum
Rejection Criteria:
Gel separator tubes
Turn Around Time:
2 days upon receipt at reference laboratory
Reference Range:
Therapeutic concentration: 2.0-5.0 mcg/mL
Toxic concentration: > or =10.0 mcg/mL
Comments:
This test is not useful for evaluation of the patient with prolonged bleeding who are suspected of exposure to rat poisons.

Patients transfused with fresh-frozen plasma may have a disparity between their warfarin level (elevated) and a relatively normal prothrombin.
Methodology:
High-Pressure Liquid Chromatography (HPLC)
CPT Code:
82542