How to manage a patient on warfarin with an elevated INR?

Management of INR 5.5 on Warfarin 7mg Daily

For a patient on warfarin with INR 5.5 and no active bleeding, withhold the next 1-2 doses of warfarin and administer oral vitamin K 1-2.5 mg, then recheck INR within 24-48 hours. 1, 2

Immediate Actions

• Stop warfarin immediately until INR falls back into therapeutic range 1, 2
• Administer oral vitamin K 1-2.5 mg because this INR level (5.5) falls in the 5-9 range where vitamin K is recommended, particularly if the patient has any bleeding risk factors 1, 2
• The oral route is preferred over IV administration due to predictable effectiveness, convenience, and avoidance of anaphylactic reactions (which occur in 3 per 100,000 IV doses) 1, 2

Expected Response to Treatment

• After oral vitamin K 1-2.5 mg, 95% of patients will show INR reduction within 24 hours, with 85% achieving INR <4.0 1, 2
• Without vitamin K, simply withholding warfarin would take 4-5 days for INR to normalize 1
• The low-dose vitamin K approach (1-2.5 mg) avoids warfarin resistance that occurs with high doses (10 mg), which can persist for up to a week 1, 2

Monitoring Protocol

• Recheck INR within 24-48 hours after intervention to confirm appropriate reduction 2
• Continue monitoring every 24-48 hours until INR stabilizes in therapeutic range 2, 3
• If INR remains elevated at 24 hours, consider additional 1-2 mg vitamin K 1

Restarting Warfarin

• Resume warfarin at a reduced dose (approximately 10-20% lower than previous weekly total) when INR falls below 3.5 2, 3
• For this patient on 7 mg daily (49 mg weekly), restart at approximately 5.5-6 mg daily when INR is therapeutic 3
• Critical: Investigate the cause of INR elevation before resuming therapy—look for new medications (especially antibiotics, antifungals, NSAIDs), dietary changes (decreased vitamin K intake), compliance issues, acute illness, alcohol use, or changes in liver/renal function 2, 3

Risk Stratification Considerations

• Even at INR 5.5, the absolute daily risk of bleeding remains relatively low, but risk increases exponentially above 5.0 1, 2
• Bleeding risk factors that warrant vitamin K administration include: advanced age (>65 years), history of bleeding, concomitant antiplatelet drugs, renal failure, alcohol use, or treated hypertension 1, 4
• If this patient has any of these risk factors, vitamin K is strongly indicated rather than observation alone 1, 2

What NOT to Do (Critical Pitfalls)

• Do not use high-dose vitamin K (10 mg) as this causes overcorrection, warfarin resistance for up to a week, and difficulty re-establishing therapeutic anticoagulation 1, 2
• Do not use IV vitamin K unless there is active bleeding, due to anaphylactic risk 1, 2
• Do not restart warfarin at the original 7 mg dose without reduction, as this will likely lead to recurrent supratherapeutic INR 3
• Do not use subcutaneous vitamin K as absorption is unpredictable and often delayed 1, 5

When to Escalate Management

• If any bleeding develops (even minor), increase vitamin K dose to 5 mg orally and consider hospital evaluation 1
• If major bleeding occurs (hemoglobin drop ≥2 g/dL, critical site bleeding), immediately give vitamin K 5-10 mg IV by slow infusion over 30 minutes plus 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg IV 2, 6
• Fresh frozen plasma is inferior to PCC (takes hours vs. 5-15 minutes for effect) and should only be used if PCC is unavailable 2, 6