international normalized ratio

by: Joe Hing kwok Chu

System established by the World Health Organization and the International Committee on thrombosis and haemostasis for monitoring and reporting blood coagulation tests. 

The reagent used to achieve clot formation in the(Prothrombin Time (PT) test affects the amount of time it takes to form the clot. Reagent thromboplastin derived from either human or rabbit brain can be used. The rabbit brain thromboplastins are generally less sensitive to deficiencies in clotting proteins than those made from human brain.

The World Health Organization developed thromboplastin from human brain as a standard and all other thromboplastins have to use a correction factor uniform results of PT tests.

Under this system, results are standardized using the international sensitivity index for the particular test reagent/instrument combination used.

Also see Prothrombin Time Back to Warfarin Back to Heparin