Prothrombin time/international normalized ratio

Abstract

Prothrombin time (PT) and/or International Normalized Ratio (INR) is the most commonly used coagulation assay in health care, to diagnose the risk of bleeding and to monitor oral anticoagulation therapy. This test is based on the principle that in citrated plasma, the addition of a thromboplastin and CaCl2 allows for formation of a stable clot. The time required for the formation of a stable clot is recorded in seconds and represents the actual PT result. INR is calculated from the PT and allows for worldwide standardization of results. © 2013 Springer Science+Business Media New York.