Which lab value monitors warfarin therapy and what dietary factor can affect anticoagulation levels?

Which lab value monitors warfarin therapy and what dietary factor can affect anticoagulation levels?

• A. Platelet count; sodium intake.
• B. INR; dietary vitamin K intake affects warfarin effect; maintain consistent vitamin K intake.
• C. aPTT; calcium intake.
• D. PT; caffeine intake.

Answer: (B)

The main concept is how warfarin therapy is monitored and how diet affects its effect. Warfarin’s anticoagulant activity is tracked using the International Normalized Ratio, a standardized measure of prothrombin time that reflects how long blood takes to clot in the presence of warfarin. Because vitamin K in the diet can counteract warfarin, fluctuations in dietary vitamin K can shift the INR and change the level of anticoagulation. That’s why it’s important to maintain a consistent vitamin K intake and have INR levels checked regularly so the dose can be adjusted as needed. Platelet count and aPTT are not used to monitor warfarin; PT is related but is not standardized across labs like the INR; caffeine and calcium intake do not have a reliable impact on warfarin anticoagulation.

The main concept is how warfarin therapy is monitored and how diet affects its effect. Warfarin’s anticoagulant activity is tracked using the International Normalized Ratio, a standardized measure of prothrombin time that reflects how long blood takes to clot in the presence of warfarin. Because vitamin K in the diet can counteract warfarin, fluctuations in dietary vitamin K can shift the INR and change the level of anticoagulation. That’s why it’s important to maintain a consistent vitamin K intake and have INR levels checked regularly so the dose can be adjusted as needed. Platelet count and aPTT are not used to monitor warfarin; PT is related but is not standardized across labs like the INR; caffeine and calcium intake do not have a reliable impact on warfarin anticoagulation.