From the Guidelines
Vitamin K should not be routinely used for patients with INR values between 4.5 and 10 without evidence of bleeding, but it is suggested for patients with INR values above 10 without bleeding. For patients taking vitamin K antagonists (VKAs) with high INR values, the management strategy depends on the INR value and the presence of bleeding.
- For INR values between 4.5 and 10 without bleeding, the evidence suggests against the routine use of vitamin K 1.
- For INR values above 10 without bleeding, oral vitamin K is suggested to be administered 1. The American College of Chest Physicians guidelines provide recommendations for managing patients on coumarin anticoagulants who need their INRs lowered due to actual or potential bleeding 1. Key points to consider include:
- The risk of bleeding increases significantly when the INR exceeds 4.5 1.
- Vitamin K can be administered orally or intravenously, with oral administration being predictably effective and safe 1.
- The dose of vitamin K depends on the INR value, with higher doses required for higher INR values 1. It is essential to monitor the INR regularly after administering vitamin K and to inform patients that they may become temporarily resistant to warfarin after receiving vitamin K, potentially requiring higher doses when anticoagulation is restarted 1.
From the FDA Drug Label
Excessive anticoagulation, with or without bleeding, may be controlled by discontinuing warfarin sodium tablets therapy and if necessary, by administration of oral or parenteral vitamin K1. If minor bleeding progresses to major bleeding, give 5 to 25 mg (rarely up to 50 mg) parenteral vitamin K1.
Yes, vitamin K is given for high INR, specifically in cases of excessive anticoagulation with or without bleeding, to control and reverse the effects of warfarin sodium tablets therapy 2.
- The administration of vitamin K1 can be oral or parenteral.
- The dose of parenteral vitamin K1 can range from 5 to 25 mg, and rarely up to 50 mg.
From the Research
Vitamin K Administration for High INR
- Vitamin K is used to reverse excessive anticoagulation by warfarin, with the goal of rapidly lowering the international normalized ratio (INR) into a safe range to reduce the risk of major bleeding 3.
- The use of vitamin K in patients with warfarin over-anticoagulation lowers excessively elevated INR faster than withholding warfarin alone, although it has not been clearly demonstrated that vitamin K treatment lowers the risk of major hemorrhage 3.
- Oral administration of vitamin K is preferred, with a dose of 1-2.5mg of oral phytomenadione (vitamin K(1)) reducing the range of INR from 5.0-9.0 to 2.0-5.0 within 24-48 hours 3.
Effectiveness of Vitamin K
- Vitamin K begins reversing warfarin within 6 to 12 hours, with a significant decrease in INR values compared to baseline INR 4.
- High vitamin K doses and intravenous route are associated with rapid INR change and complete reversal, although overall complete reversal at 24 and 48 hours is low 4.
- Baseline INR also influences the rate of correction and frequency of achieving complete reversal, with higher baseline INR associated with rapid INR change and lower baseline INR with complete reversal 4.
Management of Excessive Anticoagulation
- Unexpectedly elevated INR values may be treated with either simple warfarin withdrawal or the administration of low doses of oral vitamin K, with oral vitamin K more rapidly returning the INR to the therapeutic reference interval 5.
- If the INR is in excess of 10, most experts recommend the administration of vitamin K and, in the case of active bleeding, additional administration of coagulation factors either in the form of fresh frozen plasma (FFP) or prothrombin complex concentrates (PCC) 5.
- Prothrombin complex concentrates (PCC) are associated with a significant reduction in all-cause mortality compared to FFP, as well as more rapid INR reduction and less volume overload without an increased risk of thromboembolic events 6, 7.