Abstract
It has been known that bovine tissue thromboplastin reacts more with activated human factor VII than with non-activated factor VII, whereas human tissue thromboplastin interacts equally with both activated and non-activated human factor VII. Thus the ratio of factor VII activity measured with bovine tissue thromboplastin to that measured with human tissue thromboplastin (b/h) reflects the relative amount of activated factor VII. In this report, we provide evidence that the b/h ratio is a very sensitive and specific indicator of the stages of accelerated coagulation. Upon activation of the extrinsic coagulation pathway by addition of a smal amount of tissue thromboplastin to blood in a plastic tube, the b/h ratio was increased from 1.0 to 1.6. The ratio was increased up to 1, 000-fold by cold induced activation of factor VII in plasma from pregnant women. In vitro activation of the intrinsic pathway by incubation of plasma in a glass tube at 37°C or by addition of kaolin raised the b/h ratio up to 98-fold and 8-fold, respectively. Patients in hypercoagulable state were divided into three groups; group A (non-DIC), group B (pre-DIC), and group C (DIC). The b/h ratios in group A (1.393±0.782) and in group C (1.260±0.455) were not significantly different from that of normal controls (1.086±0.154). However, in group B, the b/h ratio (2.868±1.993) was significantly higher than that in normal controls (p<0.05). Several lines of evidence indicated that the increased b/h ratio in group B plasmas was the result of accelerated activation of factor VII due to hypercoagulability. Thus, the b/h ratio would be a useful clinical marker to detect hypercoagulable state such as pre-DIC.
