Doctor's Assessment Included
Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
INR
INR monitoring is especially important for older adults, who are more commonly on anticoagulant therapy and more sensitive to warfarin dose changes.
What It Measures
INR is calculated from the prothrombin time using an international sensitivity index. A normal INR is approximately 1.0. Higher values indicate slower clotting. Therapeutic range for warfarin is typically 2.0-3.0.
Why It Matters
INR monitoring ensures anticoagulant therapy remains in the therapeutic range — high enough to prevent clots but not so high as to cause bleeding. INR also reflects liver function since the liver produces most clotting factors.
When to Test
INR is regularly monitored in patients on warfarin, before surgery, when liver disease is suspected, or as part of coagulation assessment.
Symptoms
Low Levels
A low INR (below therapeutic range in warfarin users) suggests insufficient anticoagulation and increased clotting risk. Dose adjustment may be needed.
High Levels
A high INR indicates excessive anticoagulation and increased bleeding risk. Symptoms may include easy bruising, nosebleeds, blood in urine or stool, and prolonged bleeding from minor cuts.
Lifestyle Tips
If on warfarin, maintain consistent vitamin K intake (green leafy vegetables), avoid sudden dietary changes, limit alcohol, inform all healthcare providers about your anticoagulant use, and attend regular INR monitoring appointments.
Frequently Asked Questions
What is a normal INR?
For people not on anticoagulants, normal INR is approximately 0.8-1.2. For warfarin therapy, the target is usually 2.0-3.0.
Why is INR monitoring important on warfarin?
Warfarin has a narrow therapeutic window. Too low and you risk clots; too high and you risk bleeding. Regular INR monitoring keeps you in the safe range.
Do DOACs require INR monitoring?
No. Direct oral anticoagulants (DOACs like rivaroxaban, apixaban) do not require routine INR monitoring.