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Updated: Aug 17, 2018

Vitamin K dependent clotting factors made in the liver include the clotting factors II, VII, IX and X as well as the anticoagulant proteins, protein C and protein S. Warfarin is a Vitamin-K antagonist and works to block its effects in the production of these clotting factors. Tests used to measure these clotting factors include the PT/INR which become prolonged with the use of warfarin. Warfarin therapy is closely monitored via the PT/INR tests to avoid toxicities such as the formation of clots/stroke etc.

If a patient comes in with a very high INR and needs an urgent reversal of the drug (such as in acute major bleeding/ trauma, urgent surgery or invasive procedure, actively bleeding etc), we can give prothrombin complex concentrate (PCC, trade name K centra). PCC contains clotting factors II, VII, IX and X as well as protein C and protein S.

Dosing of Kcentra depends on the patient's weight and pre-treatment INR level.

dosing for warfarin reversal:

INR Dose (IU/kg) Max Dose (IU)

2-4 25 2500

4-6 35 3500

>6 50 5000

*Sometimes we get consulted for patients (such as those with liver disease) who are not taking warfarin, but are found to have an elevated INR, but need an emergent surgery/procedure. This is off-label usage, but our experience of giving typically a lower dose (10-15 units/kg) for these patients has had no adverse effects thus far. Consult your Pathologist prior to making any decision.

For more details about dosing Kcentra, visit the manufacturer's website:

They also have an app you can download for dosing assistance. (I am in no way affiliated with this company and do not receive any financial reimbursement for this endorsement.)

I have also made a calculator (among many other transfusion medicine handy-dandy calculators) that you can access from this website simply by clicking on the "Calculators" tab at the top of the screen.


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