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.
Related biomarkers
Source: MedlinePlus, U.S. National Library of Medicine