In a patient recently started on warfarin, with a significant drop in hemoglobin levels, would you hold the warfarin for that day?

Warfarin Management with Hemoglobin Drop from 113 to 105 g/L

Yes, you should hold the warfarin immediately in this patient with a hemoglobin drop of 8 g/L in one day, as this represents clinically significant bleeding that warrants stopping oral anticoagulation and initiating measures to identify and control the bleeding source. 1

Rationale Based on Major Bleeding Criteria

The American College of Cardiology defines a major bleed as meeting any of the following criteria 1:

• Bleeding at a critical site
• Hemodynamic instability
• Clinically overt bleeding with hemoglobin decrease ≥2 g/dL (equivalent to ≥20 g/L)
• Administration of ≥2 units of red blood cells

While your patient's drop of 8 g/L (0.8 g/dL) does not meet the strict ≥2 g/dL threshold for major bleeding, this represents a significant acute decline that suggests active bleeding requiring immediate attention 1.

Immediate Management Steps

Stop the warfarin immediately and initiate appropriate measures to control bleeding, even though this technically qualifies as a non-major bleed by strict criteria 1. The key considerations are:

• The bleeding is occurring in a patient recently started on warfarin, meaning they are in the high-risk initiation phase where INR may be rising and bleeding risk is elevated 2
• An 8 g/L drop in 24 hours indicates ongoing blood loss that could rapidly progress to meet major bleeding criteria 1
• The source of bleeding must be identified urgently, as occult bleeding (gastrointestinal, retroperitoneal, etc.) can be life-threatening 1

Assessment of INR and Reversal Needs

Check the INR immediately to guide further management 2:

• If INR is therapeutic (2.0-3.0) but bleeding is occurring, this confirms the bleeding is clinically significant enough to warrant holding warfarin 1
• If INR >5 without overt major bleeding, consider oral vitamin K 1-2.5 mg if the patient has bleeding risk factors 2, 3
• If INR >9, administer oral vitamin K 3-5 mg 2
• Do not give reversal agents (prothrombin complex concentrates, fresh frozen plasma) unless the bleeding progresses to major bleeding with hemodynamic instability 1

Monitoring and Investigation

While warfarin is held 1:

• Recheck hemoglobin within 6-12 hours to assess trajectory of decline
• Check INR daily until the bleeding source is identified and controlled 2
• Investigate the bleeding source aggressively: examine for gastrointestinal bleeding (melena, hematochezia), genitourinary bleeding (hematuria), or occult bleeding sites 1
• Assess for hemodynamic stability repeatedly, as progression to major bleeding would require escalation to reversal agents 1

When to Restart Warfarin

The American College of Cardiology recommends delaying restart of anticoagulation if any of the following apply 1:

• Source of bleeding has not yet been identified
• Patient is at high risk of rebleeding
• Bleeding occurred at a critical site

Once the patient is stable and the bleeding source is identified and controlled, warfarin can be restarted at a 20-30% lower weekly dose than previously prescribed 3. Continue monitoring INR 2-3 times weekly initially after restart 2.

Critical Pitfall to Avoid

Do not continue warfarin simply because the hemoglobin drop doesn't meet the strict ≥2 g/dL threshold for major bleeding 1. In a patient recently started on warfarin, any significant unexplained hemoglobin drop represents a red flag for bleeding that could rapidly progress. The conservative approach of holding warfarin, investigating thoroughly, and restarting cautiously is the safest strategy 1, 2.