Which statement about monitoring Warfarin therapy during PN transitions is true?

• A. INR should be monitored closely to maintain the therapeutic range during transitions
• B. INR is not affected by transitions
• C. Warfarin dose should be stopped completely during PN transitions
• D. Vitamin K should be reduced to zero during transitions

Answer: (A)

During transitions of parenteral nutrition, the effect of warfarin on anticoagulation can change because the amount of vitamin K and other PN components influencing warfarin metabolism may vary. Warfarin has a narrow therapeutic window, so small shifts in INR can move you from a safe range to risk of bleeding or thrombosis. Because PN transitions can alter vitamin K intake, fluid status, liver function, and drug interactions, the INR is likely to fluctuate. Monitoring it closely allows timely dose adjustments so the patient remains within the therapeutic range as the PN transition is completed and stabilized.

The statement that INR is not affected by transitions is inconsistent with how warfarin responds to changes in vitamin K and metabolic conditions. Stopping the warfarin completely during PN transitions is not routinely indicated and can increase thrombosis risk, while reducing vitamin K exposure to zero is inappropriate and can provoke unpredictable INR shifts.