International Normalized Ratio
INR (International Normalized Ratio) is a standardized measure of blood coagulation derived from the prothrombin time (PT). It reflects the activity of the extrinsic coagulation pathway, which depends on liver-synthesized clotting factors (II, VII, IX, X).
It is a host/organ-function biomarker.
| Elevated INR Usually Means | Clinical Interpretation |
| ---------------------------------- | --------------------------------------------------- |
| Reduced hepatic synthetic function | Liver involvement, cirrhosis, or treatment toxicity |
| Vitamin K deficiency | Malnutrition, cholestasis, antibiotics |
| Consumptive coagulopathy | Advanced cancer, sepsis |
| Anticoagulant effect | Warfarin or drug interactions |
In cancer, rising INR often signals systemic decline, not just a lab abnormality.
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