How to manage a patient with a supratherapeutic International Normalized Ratio (INR) of 6?

Management of Supratherapeutic INR of 6

For a patient with an INR of 6 without evidence of bleeding, the next 1-2 doses of warfarin should be omitted and vitamin K₁ 1-2.5 mg should be administered orally, especially if the patient has risk factors for bleeding. 1

Assessment Algorithm

1. Evaluate for bleeding:

   • Check for overt bleeding (gastrointestinal, genitourinary, intracranial)
   • Assess for signs of occult bleeding (hypotension, tachycardia, decreased hematocrit)
   • Perform physical examination focusing on potential bleeding sites

2. Assess risk factors for bleeding:

   • Age >65 years
   • History of stroke or gastrointestinal bleeding
   • Comorbidities like renal insufficiency or anemia
   • Concomitant use of antiplatelet agents, NSAIDs, or other drugs affecting coagulation
   • Recent trauma

Management Plan

For INR of 6 without bleeding:

1. Immediate management:

   • Omit the next 1-2 doses of warfarin 1
   • Administer vitamin K₁ 1-2.5 mg orally, particularly if patient has bleeding risk factors 1
   • Monitor INR within 24 hours to assess response

2. Follow-up:

   • Restart warfarin at a lower dose when INR approaches therapeutic range 1
   • Consider more frequent INR monitoring initially after restarting warfarin
   • Investigate potential causes of elevated INR (drug interactions, dietary changes, etc.)

For INR of 6 with bleeding:

1. Minor bleeding:

   • Omit warfarin doses
   • Administer vitamin K₁ 2-5 mg orally 1
   • Monitor INR more frequently (every 12-24 hours)
   • Local measures to control bleeding

2. Major bleeding:

   • Administer vitamin K₁ 10 mg by slow intravenous infusion 1
   • Supplement with fresh plasma or prothrombin complex concentrate 1
   • Admit for close monitoring
   • Additional doses of vitamin K₁ may be necessary every 12 hours 1

Important Considerations

• Risk of thrombosis: While managing elevated INR, consider the patient's underlying indication for anticoagulation. Patients with mechanical heart valves or recent thromboembolism are at higher risk when anticoagulation is reversed 1

• Vitamin K dosing caution: High doses of vitamin K₁ may create warfarin resistance for up to a week. Use the lowest effective dose needed to reduce bleeding risk 1

• Medication review: Identify and address any potential drug interactions that may have contributed to the elevated INR (antibiotics, NSAIDs, acetaminophen) 1, 2

• Patient education: Instruct the patient about dietary consistency regarding vitamin K-containing foods and to avoid self-medication with over-the-counter products that might interact with warfarin

• Monitoring after intervention: After vitamin K administration, monitor INR closely as additional doses may be needed if INR remains elevated 1

The risk of bleeding increases significantly when INR exceeds 4.5, and rises sharply with values >5 1. Therefore, prompt intervention for an INR of 6 is essential to prevent potentially serious bleeding complications while balancing the risk of thromboembolism from inadequate anticoagulation.