Warfarin Management in Hematuria
Do not automatically discontinue or reduce warfarin when hematuria occurs; instead, maintain therapeutic anticoagulation while urgently investigating for underlying urologic pathology, as hematuria in anticoagulated patients frequently indicates significant disease (malignancy, stones, infection) requiring prompt diagnosis and treatment. 1, 2, 3
Critical First Principle: Hematuria is a Red Flag, Not Just a Side Effect
The presence of hematuria in a patient on warfarin—even with a therapeutic INR—should trigger immediate urologic evaluation rather than reflexive dose reduction. Studies demonstrate that 59-83% of anticoagulated patients with hematuria have significant underlying pathology including bladder cancer, renal cell carcinoma, stones, or infection. 2, 3 Bleeding at an INR ≤3.0 is frequently associated with an underlying lesion in the genitourinary tract that requires identification. 1
Immediate Assessment Algorithm
Step 1: Check INR and Assess Bleeding Severity
- If INR is therapeutic (2.0-3.0) with hematuria: Continue warfarin at current dose and proceed immediately to urologic workup 1, 2
- If INR is 3.0-5.0 with mild hematuria: Continue warfarin but recheck INR in 1-2 days while initiating urologic evaluation 4, 5
- If INR is 5.0-9.0 without active bleeding: Hold warfarin temporarily and give oral vitamin K₁ 1-2.5 mg if bleeding risk factors present; resume at lower dose once INR normalizes 6, 7
- If INR >9.0 or significant bleeding: Give oral vitamin K₁ 3-5 mg and hold warfarin until INR falls to therapeutic range 6, 7
Step 2: Mandatory Urologic Workup
Regardless of INR level, all patients with hematuria on warfarin require: 2, 3
- Urinalysis with microscopy
- Renal ultrasound or CT urography
- Cystoscopy
- Urine cytology if risk factors for malignancy present
This evaluation should not be delayed or deferred based on the assumption that anticoagulation alone explains the bleeding. 2
Long-Term Management After Evaluation
If Significant Pathology Found (Cancer, Stones, Infection)
- Treat the underlying condition definitively 2, 3
- If warfarin must be continued and bleeding occurred within therapeutic range (INR 2.0-3.0), reduce target to INR 2.0-2.5 for mechanical valves or INR 1.5-2.0 for atrial fibrillation, accepting some reduction in efficacy 1
- Consider aspirin as alternative for lower-risk atrial fibrillation patients 1
If No Pathology Found
- Resume warfarin at previous therapeutic dose 1
- Maintain standard INR target (2.0-3.0 for most indications) 8
- Monitor more frequently initially 5
Common Pitfalls to Avoid
Do not assume hematuria is simply "expected" on anticoagulation. Even patients at low risk for urologic malignancy (non-smokers, no carcinogen exposure) can harbor early-stage cancers detectable only through prompt evaluation. 2 One case report documented poorly differentiated transitional cell carcinoma in a 63-year-old with stable therapeutic anticoagulation and no traditional risk factors—early detection allowed curative surgery. 2
Do not empirically reduce warfarin dose before completing urologic workup. This delays diagnosis of potentially life-threatening conditions while exposing the patient to thromboembolic risk. 1, 2
Do not use high-dose vitamin K (10 mg) unless life-threatening bleeding occurs, as this causes warfarin resistance for up to one week. 6 For INR 5.0-9.0, use only 1-2.5 mg oral vitamin K₁; for INR >9.0, use 3-5 mg. 6, 7
Risk Factor Considerations
Age >65 years significantly increases bleeding risk even at therapeutic INR levels. 1, 6 These patients warrant more conservative INR targets (lower end of 2.0-3.0 range) after hematuria episodes, but still require complete urologic evaluation. 1, 6
Concomitant use of aspirin, NSAIDs, or other antiplatelet agents dramatically amplifies bleeding risk and should be discontinued if medically feasible. 1, 6