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FeedbackWarfarin is an oral anticoagulant that must be carefully monitored to keep a patient’s international normalized ratio (INR) within a very narrow range. When the INR is outside this range, the patient either clots or bleeds too much. The INR reflects a dose change made 2-6 days prior to the patient’s blood being collected. If a patient’s dose has been adjusted too high and there is a risk of a bleeding event, vitamin K is administered to reverse the anticoagulation actions.
Warfarin monitoring varies between clinical settings (acute vs ambulatory). Healthcare facilities should have consistent dosing protocols in place to monitor therapy so that care does not vary between staff shifts or providers.
See the ARUP Consult topic Hypercoagulable States for additional information.
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Johnson JA, Caudle KE, Gong L, et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Pharmacogenetics-Guided Warfarin Dosing: 2017 Update. Clin Pharmacol Ther. 2017;102(3):397-404.