The Progress of Prothrombin Time to a New Generation Method for INR: The Progress of Prothrombin Time Method

Oral anticoagulation therapy (OAT)is one of the most common medication regimens. The narrow therapeutic window means risk of bleeding or thrombosis. The prothrombin time test (PT) was introduced by professor Armand Quick in 1935 more than 70 years ago to monitor this therapy. Over twenty years later professor Paul Owren developed a new PT method (combined thromboplastin reagent) to overcome the drawbacks of the Quick PT method. Both methods are today accepted for anticoagulant therapy control.The WHO recommendation in 1985 for the use of INR aims to harmonize PT results for OAT regardless of the reagent, instrument or method used.Warfarin (or Coumarin) inhibits the synthesis of K-vitamin dependent coagulation factors in the liver,but at the same time blocked inactive coagulation factors are formed.Quick and Owren PT methods measure the sum of inhibition and active coagulation factors in the patient plasma.The new generation PT method measures active coagulation factors and inhibition separately. The new PT method develops anticoagulation therapy based on active coagulation factors in vivo and improves INR harmonization.