プロトロンビン時間による複合凝固因子低下の評価に
International Normalized Ratio(INR)表記法を
導入するための基礎的検討

藤　田　　　進*1　香　川　和　彦*2　福　武　勝　幸*3
　　　　　　　　　　　　　　　　　　　　　　
Introduction of International Normalized Ratio of Prothrombin Time
to Evaluate Multiple Depletions of Coagulation Factors

Susumu FUJITA, MD*1, Kazuhiko KAGAWA, MD, PhD*2
and Katsuyuki FUKUTAKE, MD, PhD*3

Prothrombin time(PT) is utilized in worldwide as a global coagulation test reflected multiple depletions of coagulation factors in diseases such as severe liver dysfunction and Disseminated Intravascular Coagulation(DIC). However, standardization of reagents and result reporting methods are not established yet except International Normalized Ration(INR) for control of oral anticoagulant therapy(OAT).
We evaluated whether INR is capable for defect of multiple coagulation factors except OAT, using absorbed plasma and different origins of thromboplastin ; human recombinant, human placenta, cultured human cell and rabbit brain. PTs of individual 90 samples(group MC) absorbed with BaSO4 and/or bentnite and 60 samples(group W) from patients with OAT were measured with 20 normal plasmas with respective reagents. Sensitivities of four reagents to plasma of group W and MC were determined respectively against human recombinant thromboplastin(ISI＝1.03).
Both of human thromboplastin showed that sensitivity to absorbed plasma was very close to OAT plasma, whereas reductions of sensitivity to 84% and 66% for absorbed plasma were revealed in both of rabbit thromboplastins. Correlations of INRs calculated by two different sensitivities, one is to absorbed plasma and another to OAT plasma, indicated that discrepancy of sensitivities was emphasized as large slopes(1.50 and 2.76) of regression lines and large intercepts in rabbit thromboplastins, although slopes closed to 1.0 with small intercepts in both of human thromboplastins.
We concluded that use of human thromboplastin was the first priority to introduce INR system for evaluation of multiple coagulation factors depletions.
[Rinsho Byori 50 : 618〜624, 2002]

*1Department of Laboratory Medicine, Tokyo Medical University, Shinjuku-ku, Tokyo 160-0023

【Key Words】Prothrombin time(プロトロンビン時間)，International Normalized Ratio：INR，Multiple depletions of coagulation factors(複合凝固因子低下)，Disseminated Intravascular coagulation(播種性血管内凝固)

受付2002年2月27日・受理2002年3月28日
*1〜3東京医科大学臨床検査医学講座(〒160-0023 東京都新宿区西新宿6-7-1)