International Normalized Ratio monitoring warfarin therapy

The International Normalized Ratio (INR) is the laboratory test used to monitor patients on anticoagulant therapy. Normal INR is 1.3 to 2.0 and patients on warfarin therapy are maintained at an INR of 2.0 to 3.0. Monitoring the lab values at regular intervals is required for the duration of drug therapy. 

Uses. Warfarin is the oral anticoagulant of choice, for it is reliably effective and has the lowest incidence of adverse effects. Monitoring of therapy is by the prothrombin time. Usually the test is carried out with a standardised thromboplastin and the result is expressed as the International Normalised Ratio (INR), which is the ratio of the prothrombin time in the patient to that in a normal (non-anticoagulated) person—taking account of the sensitivity of the... 

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