Monitoring Oral Anticoagulant Therapy by the Prothrombin Time: Reporting the Coagulation Activity or the International Normalized Ratio?

Interpretation of serial measurements of international normalized ratio for prothrombin times in monitoring oral anticoagulant therapy.

Despite careful monitoring of oral anticoagulant treatment (OAT), some international normalized ratio (INR) for prothrombin time values will fall outside the therapeutic range. Considerable changes in serial INR results from OAT patients may be caused by random fluctuation alone, and, for statistical reasons, a fraction of the INR values will fall outside therapeutic range and interfere with do...

Automated calculation of coagulation activity and International Normalized Ratio in oral anticoagulant control

Preanalytical variables and off-site blood collection: influences on the results of the prothrombin time/international normalized ratio test and implications for monitoring of oral anticoagulant therapy.

BACKGROUND The quality of oral anticoagulant therapy management with coumarin derivatives requires reliable results for the prothrombin time/International Normalized Ratio (PT/INR). We assessed the effect on PT/INR of preanalytical variables, including ones related to off-site blood collection and transportation to a laboratory. METHODS Four laboratories with different combinations of blood c...

Comparison of the native prothrombin antigen and the prothrombin time for monitoring oral anticoagulant therapy.

We have measured the fully carboxylated (native) prothrombin antigen and the undercarboxylated (abnormal) prothrombin antigen in patients treated with sodium warfarin using specific immunoassays to evaluate a new approach for monitoring oral anticoagulant therapy. Plasma and serum samples (391) were assayed for the prothrombin time, native prothrombin antigen, and abnormal prothrombin antigen. ...

Has the time arrived to replace the quick prothrombin time test for monitoring oral anticoagulant therapy?

The Quick (1 ) and Owren (2 ) prothrombin time (PT) tests remain the basis for monitoring anticoagulant therapy worldwide. The use of these tests is remarkable because the Quick PT preceded the discovery of the anticoagulant effect of dicoumarol in spoiled sweet clover and both tests were in use long before there was any understanding of the mechanism of the action of oral anticoagulants or whi...