AccuType® Warfarin

Test Code
WARFARIN (16160)

Quest Code
16160

CPT Codes
81227, 81355<br /> *The 2012 AMA CPT codebook contains Tier 1 and Tier 2 Molecular Pathology Procedures as well as Molecular Pathology Procedures to be coded by procedure rather than analyte. Please direct any questions regarding coding to the payor being billed.

Physician Attestation of Informed Consent
This germline genetic test requires physician attestation that patient consent has been received if ordering medical facility is located in AK, DE, FL, GA, IA, MA, MN, NV, NJ, NY, OR, SD or VT or test is performed in MA.

Includes
detects variants from two genes, VKORC1 and CYP2C9

Preferred Specimen
5 mL whole blood collected in an EDTA (lavender-top) tube

Minimum Volume
3 mL

Other Acceptable Specimens
Saliva • Whole blood collected in: ACD solution A (yellow-top), sodium heparin (royal blue-top), sodium heparin (green-top), ACD solution B (yellow-top) and lithium heparin (green-top)

Specimen Stability
Room temperature: 8 days
Refrigerated: 8 days

Methodology
Single Nucleotide Primer Extension

Setup Schedule
Mon, Wed, Fri

Report Available
6 to 6 Day(s)

Limitations
Variations in two genes (VKORC1 and CYP2C9) are particularly important in warfarin metabolism. VKORC1 may explain 30% of the variability in drug response between patients and changes in CYP2C9 may explain 10% of the dose variation. While significant portion of the dose variability can be accounted for by genetic factors, this testing will not determine all factors associated with dose variability.

Reference Range
See Laboratory Report

Clinical Significance
Warfarin (Coumadin®) therapy is associated with significant complications because of its narrow therapeutic index and large interpatient dosage variation necessary to achieve an optimal therapeutic response. This variation is due to both genetic and environmental factors. A promoter variant (-1639 G→A) of the Vitamin K epoxide complex subunit 1 (VCR) accounts for 25%-44% of this variability and variants of the cytochrome P enzyme C (SPCA) account for 10%-15% of this variability. Identification of these warfarin sensitive variants of the VKORC1 and the CYP2C9 genes may allow a more individualized therapy and reduced risk of bleeding complications.

Performing Laboratory
Quest Diagnostics Nichols Institute
33608 Ortega Highway
San Juan Capistrano, CA 92675



The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.