What is the recommended dose of vitamin K (Vit K) for an elevated International Normalized Ratio (INR) of 6.9?

Management of INR 6.9

For an INR of 6.9 without active bleeding, administer 5 mg of oral vitamin K to safely reduce the INR within 24-48 hours. 1

Assessment and Risk Stratification

When managing an elevated INR of 6.9, the approach depends on:

• Presence of active bleeding
• Patient's thrombotic risk (mechanical valve, recent thromboembolism)
• Clinical stability

For INR 6.9 WITHOUT Bleeding:

1. Immediate actions:

   • Hold warfarin immediately
   • Administer oral vitamin K 5 mg 1
   • The oral route is preferred over intravenous to avoid risk of anaphylaxis (occurs in 3 per 100,000 doses) 1, 2

2. Monitoring:

   • Check INR within 24 hours
   • Expect significant reduction within 24 hours
   • Resume warfarin at a reduced dose (10-20% lower) when INR returns to therapeutic range 3

For INR 6.9 WITH Bleeding:

1. For minor bleeding:

   • Hold warfarin
   • Administer oral vitamin K 5-10 mg 1
   • Monitor INR every 6-12 hours until stabilized

2. For major/life-threatening bleeding:

   • Administer intravenous vitamin K 10 mg (infuse slowly) 1
   • Administer four-factor prothrombin complex concentrate (PCC) at 35 U/kg 1
   • PCC provides more rapid and complete factor replacement than fresh frozen plasma (FFP) 1

Rationale for Vitamin K Dosing

• The risk of major bleeding increases exponentially when INR exceeds 4.5 and rises steeply above 6.0 1
• For INR >6.0, higher doses of oral vitamin K (5 mg) are recommended 1
• A 5 mg dose of oral vitamin K will reduce an INR >10 to 2.0-5.0 within 24-48 hours 2, 4
• Lower doses (1-2.5 mg) may be insufficient for an INR of 6.9 2

Special Considerations

For Patients with Mechanical Heart Valves:

• Balance the risk of valve thrombosis against bleeding risk
• Consider a slightly lower dose of vitamin K (2.5 mg) to avoid overcorrection 1
• Monitor INR more frequently (every 12 hours) 3

For Elderly Patients:

• Higher risk of bleeding complications
• Consider resuming warfarin at a lower dose (20-30% reduction) when INR normalizes 3
• More frequent INR monitoring after resumption of therapy

Potential Pitfalls

1. Overcorrection: Using too high a dose of vitamin K may lead to warfarin resistance or a prothrombotic state 2

2. Undercorrection: Using too low a dose may not adequately reduce bleeding risk 4

3. Route of administration: Intravenous vitamin K works faster (within 6 hours) but carries risk of anaphylaxis; oral vitamin K is safer but takes 24-48 hours for full effect 5

4. Underlying causes: Always investigate potential causes of elevated INR (drug interactions, dietary changes, liver disease) 1

5. Resumption of therapy: After INR normalization, resume warfarin at a reduced dose and monitor INR closely to prevent recurrent elevation 3