What INR range is associated with optimal anticoagulation?

• A. INR 2.2-2.3
• B. INR 1.0-1.5
• C. INR 3.5-4.0
• D. INR 0.5-1.0

Answer: (A)

Keeping INR within a therapeutic range is essential to balance preventing clots with avoiding bleeding. For most people on warfarin, the target window is about 2.0 to 3.0. The range 2.2 to 2.3 sits inside that window, providing effective anticoagulation with a relatively lower bleeding risk than higher values. Values around 1.0–1.5 are too low to prevent clotting reliably, while 3.5–4.0 is higher than the typical safe range and increases bleeding risk. Very low values like 0.5–1.0 are clearly subtherapeutic. So, 2.2–2.3 best reflects the balance of effective anticoagulation within the common therapeutic window.