Which test is commonly used to monitor anticoagulation status in patients taking warfarin?

Which test is commonly used to monitor anticoagulation status in patients taking warfarin?

• A. INR
• B. A1C
• C. CK-MB
• D. Troponin

Answer: (A)

Warfarin therapy is monitored by assessing how long the blood takes to clot, using the prothrombin time that is converted to the international normalized ratio. The INR standardizes PT results from different labs, allowing clinicians to compare values and adjust the warfarin dose to keep it within a therapeutic range tailored to the patient’s indication. This reflects the anticoagulant effect because warfarin slows the production of vitamin K–dependent clotting factors, prolonging PT and thus raising the INR. In contrast, A1C measures long-term blood glucose control, while CK-MB and Troponin are markers of cardiac muscle injury or stress; none of these reflect anticoagulation status. Therefore, the INR is the test used to monitor warfarin therapy.

Warfarin therapy is monitored by assessing how long the blood takes to clot, using the prothrombin time that is converted to the international normalized ratio. The INR standardizes PT results from different labs, allowing clinicians to compare values and adjust the warfarin dose to keep it within a therapeutic range tailored to the patient’s indication. This reflects the anticoagulant effect because warfarin slows the production of vitamin K–dependent clotting factors, prolonging PT and thus raising the INR. In contrast, A1C measures long-term blood glucose control, while CK-MB and Troponin are markers of cardiac muscle injury or stress; none of these reflect anticoagulation status. Therefore, the INR is the test used to monitor warfarin therapy.