General Information

UPHSM LIS Test #: 3904
Schedule: Wednesday
Testing Time: 2 days
Testing Lab: Mayo Labs

Specimen Info
Only 1 specimen type required, unless otherwise specified

Volume: 3.0 (1.1) mL Serum
Temperature: Refrigerated
Tube Type: 1 Red Top tube
Collection Info:
Spin down within 2 hours of draw.


High-Performance Liquid Chromatography (HPLC)

Clinical Utilities

Monitoring patients whose prothrombin time is inconsistent with the prescribed warfarin dose, particularly when failure to comply or surreptitious drug use is suspected.
Note: This test is not useful for evaluation of the patient with prolonged bleeding time suspected of exposure to rat poisons.

CPT Codes


* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding
is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Reference Range

Therapeutic concentration: 2.0-5.0 mcg/mL
Toxic concentration: > or =10.0 mcg/mL