What does an International Normalized Ratio (INR) of 0.83 indicate and how should it be managed?

INR of 0.83: Normal Finding Requiring No Intervention

An INR of 0.83 is within the normal range for patients not receiving anticoagulation therapy and requires no treatment or intervention. 1

Understanding the Normal INR Range

• The normal INR range for individuals not taking vitamin K antagonists (warfarin, coumadin) is approximately 0.8 to 1.2, making your value of 0.83 completely normal 1
• The INR was specifically designed and validated only for monitoring patients on warfarin or other vitamin K antagonist therapy, not as a general screening test for coagulation disorders 2
• In non-anticoagulated patients, INR values in this range indicate normal hepatic synthetic function and adequate vitamin K-dependent clotting factor production 2

Clinical Significance

• This INR value indicates normal coagulation status and does not predict bleeding risk or clotting tendency in patients not receiving anticoagulation 2
• The therapeutic target INR for most patients requiring anticoagulation is 2.0-3.0, which is intentionally elevated above the normal range to prevent thrombosis 1, 3
• An INR below 2.0 in a patient who should be anticoagulated (such as for atrial fibrillation, mechanical heart valve, or venous thromboembolism) would indicate subtherapeutic anticoagulation and increased thrombotic risk 3

When This Value Would Be Concerning

• If you are prescribed warfarin for a condition requiring anticoagulation (atrial fibrillation, mechanical heart valve, history of blood clots), an INR of 0.83 indicates inadequate anticoagulation and requires immediate dose adjustment 3
• For patients with mechanical heart valves requiring a target INR of 2.5-3.5, this value represents dangerously low anticoagulation with high thrombotic risk 3
• For patients with atrial fibrillation requiring stroke prevention (target INR 2.0-3.0), this value provides no protection against thromboembolism 1, 3

Management Algorithm

• If NOT on warfarin: No action needed; this is a normal result 1, 2
• If ON warfarin: Contact your prescribing physician immediately for dose adjustment, as you are not adequately anticoagulated and at risk for thrombotic complications 3
• For warfarin-treated patients with subtherapeutic INR, investigate potential causes including medication non-adherence, dietary changes (increased vitamin K intake from green leafy vegetables), drug interactions, or malabsorption 4

Common Pitfall to Avoid

• Never assume an INR in the "normal" range is appropriate for all patients—the target INR depends entirely on the clinical indication 3
• The Journal of Thrombosis and Haemostasis emphasizes that INR should not be used as a general coagulopathy screening test in patients not receiving vitamin K antagonists, as it lacks validity in this context 2