PT/INR is used to monitor therapy and what does INR standardize?

Prepare for the Medical Laboratory Science Module 1 Exam. Test your knowledge with flashcards and multiple-choice questions, complete with hints and explanations. Get confident for your test!

Multiple Choice

PT/INR is used to monitor therapy and what does INR standardize?

INR standardizes prothrombin time (PT) results across different thromboplastin reagents, so PT values are comparable between labs and over time for a patient on warfarin. PT reflects the extrinsic pathway of coagulation, mainly involving tissue factor and factor VII. Because different reagents can vary in sensitivity, the INR uses an International Sensitivity Index (ISI) to adjust the PT result, making it consistent regardless of the reagent used. This is why the best answer describes monitoring warfarin therapy and standardizing PT across reagents. The other options mix up the pathways or tests: INR is not used to monitor the intrinsic pathway (that’s the PTT), nor is it about platelet function, bleeding time, or fibrinogen levels.

INR standardizes prothrombin time (PT) results across different thromboplastin reagents, so PT values are comparable between labs and over time for a patient on warfarin. PT reflects the extrinsic pathway of coagulation, mainly involving tissue factor and factor VII. Because different reagents can vary in sensitivity, the INR uses an International Sensitivity Index (ISI) to adjust the PT result, making it consistent regardless of the reagent used. This is why the best answer describes monitoring warfarin therapy and standardizing PT across reagents. The other options mix up the pathways or tests: INR is not used to monitor the intrinsic pathway (that’s the PTT), nor is it about platelet function, bleeding time, or fibrinogen levels.

More practice questions