international normalized ratio


international normalized ratio (INR),

the prothrombin time ratio that would have been obtained if a standard reagent had been used in a prothrombin time determination; the prothrombin time ratio is expressed as the patient prothrombin time divided by the mean of the prothrombin time reference interval; the prothrombin time ratio is obtained for a working reagent in the laboratory through use of a parameter designated the international sensitivity index. Compare: international sensitivity index.

international normalized ratio

(ĭn′tər-năsh′ə-nəl)n. A standardized measure of the clotting ability of blood based on the ratio of an individual's prothrombin time to the normal mean prothrombin time, used especially to monitor the risk of bleeding in patients receiving anticoagulant therapy.

International Normalized Ratio

Hematology A method of reporting prothrombin time–PT results for Pts receiving oral anticoagulant therapy; the INR is defined by the formula, PTPatient/PTMNPTISI that uses the international sensitivity index to adjust PT results from thromboplastin of different sources and facilitates monitoring anticoagulant therapy when using more than one lab and comparing a Pt's PT results with published standards for treatment. See Anticoagulation, International sensitivity index, Prothrombin time.

in·ter·na·tion·al nor·mal·ized ra·ti·o

(INR) (in'tĕr-nash'ŭn-ăl nōr'măl-īzd rā'shē-ō) The prothrombin time ratio that would have been obtained if a standard reagent had been used in a prothrombin time determination; the prothrombin time ratio is expressed as the patient's prothrombin time divided by the mean of the prothrombin time reference interval; the prothrombin time ratio is obtained for a working reagent in the laboratory through use of a parameter designated the international sensitivity index.
See also: international sensitivity index