Management of INR 6.8 on Warfarin Without Bleeding
For a patient on warfarin with INR 6.8 and no bleeding, you should administer oral vitamin K 5 mg and withhold warfarin until the INR falls back into therapeutic range. 1
Rationale for Vitamin K Administration
The American College of Cardiology specifically recommends oral vitamin K 5 mg for patients with INR >10 without bleeding 1, and while this patient's INR is 6.8, the evidence strongly supports vitamin K use at this level given the exponentially increasing bleeding risk above INR 5.0 2
The bleeding risk becomes clinically significant at INR >5.0, with one prospective series showing 3.9% major bleeding rate at 90 days even without initial bleeding at presentation 1
Among outpatients with INR >9 receiving warfarin, 11% experienced bleeding within 14 days of follow-up 3, demonstrating that even asymptomatic patients face substantial short-term hemorrhage risk
Why Not Just Observation?
The American College of Chest Physicians recommends against routine vitamin K use for INR 4.5-10 without bleeding (Grade 2B) 1, but this recommendation is nuanced by bleeding risk factors
You should add vitamin K if the patient has increased bleeding risk factors including advanced age (>65 years), history of bleeding, concomitant antiplatelet drugs, renal failure, or alcohol use 1, 4
At INR 6.8, the patient sits in a gray zone where clinical judgment about bleeding risk factors becomes critical—if any high-risk features are present, vitamin K 1-2.5 mg orally is appropriate 4
Dosing Algorithm
For INR 6.8 without bleeding:
- Withhold warfarin completely until INR falls back into therapeutic range 1, 4
- Administer oral vitamin K 1-2.5 mg if bleeding risk factors present 4
- Consider oral vitamin K 5 mg if you want more aggressive reversal given proximity to the INR >10 threshold 1
Oral route is preferred because it provides predictable effectiveness, convenience, and safety compared to parenteral routes, with 95% of patients showing INR reduction within 24 hours and 85% achieving INR <4.0 4
Monitoring Strategy
- Recheck INR within 24-48 hours after intervention to confirm appropriate decline 1, 4
- Without vitamin K, approximately 33% of patients with INR >6.0 will have INR <4.0 within 24 hours, 55% within 48 hours, and 73% within 72 hours 5
- With oral vitamin K administration, the INR typically decreases within 24 hours in 95% of patients 4
Critical Pitfalls to Avoid
- Do not use high-dose vitamin K (≥10 mg) for non-bleeding situations, as this creates warfarin resistance for up to a week and makes re-anticoagulation difficult 1, 4
- Do not use subcutaneous vitamin K, as it is less effective than oral or IV routes 6
- Do not give IV vitamin K unless there is active bleeding, as anaphylactoid reactions occur in 3 per 100,000 doses and can result in cardiac arrest 1
- Avoid simply reassessing after 2 days without any intervention, as outpatients with INR >6.0 face a 4.4% risk of major hemorrhage within 14 days 5