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Vitamin K may not be necessary

Low dose oral vitamin K didn’t reduce bleeding in patients who have been overanticoagulated on warfarin, according to a U.S. study.

The study suggests that withdrawal of warfarin may be all that is needed to manage those patients.

Note: This article is a review of a study and is not intended to offer medical advice.

The vitamin K study

Study objective. Low dose oral vitamin K is often used to decrease the INR in overanticoagulated patients who receive warfarin therapy. The researchers wanted to see if vitamin K reduces bleeding events in patients taking warfarin.

Researchers studied 724 patients with INR values between 4.5 to 10 from clinics in Canada, U.S. and Italy. Half the group was given oral Vitamin K (1.25 mg) and the other half a placebo. Only non bleeding patients were recruited and were tracked for a period of 90 days.

Study results. Among patients with an INR between 4.5 and 10.0, bleeding and thromboembolism was not increased when warfarin was stopped without initiating vitamin K. The difference in bleeding events between the 2 groups was only 0.5%.

As expected, vitamin K use was associated with a fast decrease in INR. The day after starting vitamin K, 41.6% of patients had an INR between 2.0 and 3.0, compared to 10.1% of those taking placebo.

The average decrease was 2.8 INR units in the vitamin K group, compared to 1.4 units for those taking a placebo.

The researchers conclusion

In conclusion the researchers from McMaster University wrote, “Low-dose oral vitamin K did not reduce bleeding in warfarin recipients with INRs of 4.5 to 10.0.”

They added that the results support, “the practice of treating patients with INRs between 4.5 and 10.0 with simple warfarin therapy withdrawal and reinstitution once the INR has decreased to the desired range.”

The study titled Oral Vitamin K Versus Placebo to Correct Excessive Anticoagulation in Patients Receiving was published in the Annals of Internal Medicine.

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