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Question 1 of 31

Which of the following tests are used to monitor antithrombotic therapy? I. International normalized ratio (INR) II. Activated partial thromboplastin time (APTT) III. Heparin assay

Rationale:
International normalized ratio (INR), activated partial thromboplastin time (APTT), and heparin assay are all used to monitor antithrombotic therapy. INR monitors warfarin therapy by assessing clotting time. APTT measures heparin effectiveness by evaluating intrinsic and common coagulation pathways. Heparin assays provide quantitative heparin levels, essential for adjusting doses accurately during treatment. A: If I only is correct Limited to INR, this omits APTT and heparin assays, which are crucial for monitoring different antithrombotic agents, rendering it incomplete. B: If III only is correct Restricting to heparin assay ignores INR and APTT’s roles in warfarin and heparin monitoring, respectively, missing comprehensive therapy assessment. D: If II and III are correct Excluding INR neglects warfarin monitoring, a fundamental aspect of antithrombotic therapy, making this option insufficient for full therapeutic evaluation.