PT and INR are used to monitor which medication?

PT and INR are used to monitor which medication?

• A. Heparin
• B. Enoxaparin
• C. Warfarin (Coumadin)
• D. Aspirin

Answer: (C)

PT and INR are tests used to monitor warfarin therapy, because warfarin changes vitamin K–dependent clotting factors and delays clot formation. PT measures how long plasma takes to clot after tissue factor and calcium are added, reflecting the extrinsic pathway. INR standardizes the PT result across different labs, giving a single value to guide dose adjustments. Keeping the INR in the target range helps balance preventing clots with minimizing bleeding risk, and the exact target can vary by indication. Other anticoagulants are monitored differently: heparin is typically tracked with the aPTT, low molecular weight heparin like enoxaparin is monitored by anti-Xa levels in certain situations, and aspirin, an antiplatelet, does not use PT/INR for monitoring.

PT and INR are tests used to monitor warfarin therapy, because warfarin changes vitamin K–dependent clotting factors and delays clot formation. PT measures how long plasma takes to clot after tissue factor and calcium are added, reflecting the extrinsic pathway. INR standardizes the PT result across different labs, giving a single value to guide dose adjustments. Keeping the INR in the target range helps balance preventing clots with minimizing bleeding risk, and the exact target can vary by indication.

Other anticoagulants are monitored differently: heparin is typically tracked with the aPTT, low molecular weight heparin like enoxaparin is monitored by anti-Xa levels in certain situations, and aspirin, an antiplatelet, does not use PT/INR for monitoring.