INR
INR (International Normalized Ratio) standardizes prothrombin time results across different laboratories. It is primarily used to monitor blood-thinning therapy.
Category: Coagulation
Also known as: inr, international normalized ratio, pt/inr
Reference range: 0.8–1.1 ratio (Source: ABIM)
Standard unit: ratio
High values may indicate
High INR may indicate increased bleeding risk, excessive anticoagulant medication effect, liver disease, or vitamin K deficiency.
Low values may indicate
Low INR values are normal for people not on blood thinners. In patients on warfarin, a low INR may indicate insufficient anticoagulation and increased clotting risk.
Frequently asked questions
- What is a normal INR level?
- A typical reference range for INR is 0.8–1.1 ratio (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is INR measured in?
- INR is most commonly reported in ratio. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do INR reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track INR over time?
- Yes. Upload results from any lab and BloodId charts your INR over time against its reference range, so you can see whether the trend is rising, falling, or stable.