A client taking warfarin 5 mg/day for atrial fibrillation has an INR of 3.8. The nurse would categorize the INR as what?

• A. Within normal range
• B. Low INR range
• C. Elevated INR range
• D. Low average INR range

Answer: (C)

INR measures how long the blood takes to clot, standardized so results are comparable. For atrial fibrillation, the expected therapeutic range is about 2.0 to 3.0. An INR of 3.8 means the blood is clotting even more slowly than the target, which is over-anticoagulated. That’s why this value is described as an elevated INR range. The normal INR is roughly 0.8 to 1.2, so 3.8 sits well above normal and above the desired therapeutic goal, increasing the risk of bleeding. Management would involve adjusting or holding warfarin and rechecking the INR, with monitoring for any bleeding signs.