Understanding Your Warfarin Sensitivity Test Results

What dose of warfarin will be safe and effective for you?

Find out if you are at risk - get tested

Test Type Testing Time Fee

All orders received before 3pm PST / 6pm EST are shipped out the same business day. All orders received after 3pm PST / 6pm EST or on weekends or holidays are shipped out the following business day. 24/7 online status check and account management available for all tests.


The amount of warfarin required to achieve an effective and safe dose is determined by the dosing algorithm provided by WarfarinDosing.org (http://www.warfarindosing.org/Source/Home.aspx).

Patient Information is entered/selected in the corresponding boxes: Age, sex, ethnicity, race, weight, height, smoking status, presence or absence of liver disease, indication, baseline international normalized ratio (INR), target INR and current medications (Amiodarone/Cordarone® Dose:, Statin/HMG CoA Reductase Inhibitor, any azole and Sulfamethoxazole/Septra/Bactrim/Cotrim/Sulfatrim).

The SNP results of the Warfarin Sensitivity DNA Test are selected from the drop-down boxes in the ‘Genetic Information’ section of WarfarinDosing.org, as per the table below. The Warfarin Sensitivity DNA Test provides results for more SNPs than are currently included in the WarfarinDosing.org algorithm. At present, the extra results are excluded from the algorithm.

Drop-down Box

SNP Result



CYP4F2 V433M


GGCX rs11676382










1 Select ‘A- (heterozygous)’ for an ‘AG’ result or ‘– (homozygous mutant)’ for a ‘GG’ result)

The algorithm calculates an initial warfarin dose requirement and an estimated daily warfarin dose requirement, in order to achieve the target international normalized ratio (INR).

The WarfarinDosing.org website is provided by the Warfarin Dose Refinement (DR) Collaboration and IWPC (a group of international collaborations of biostatisticians, geneticists, pharmacists, and physicians who share anonymous data to improve warfarin dosing). WarfarinDosing.org is an independent website and is not under the control of our laboratory. The algorithm provided by WarfarinDosing.org is continually updated to ensure it provides an accurate and safe warfarin dose estimate. Our laboratory holds no responsibility for the content and availability of WarfarinDosing.org.

Next, Getting the Warfarin Sensitivity DNA Test »