Acute phase reaction, fibrinogen level and thrombus size.

The influence of an acute phase reaction on the size, weight, and fibrin content of experimental venous thrombi was examined in 10 pairs of rabbits. Jugular vein thrombosis was provoked by venous stasis plus mechanical injury 36 hours after one member of each pair received 0.5 ml/kg sterile turpentine in olive oil by subcutaneous injection. Fibrinogen level, factor VIII activity, and antithrombin III activity were significantly higher at the time of thrombus formation in turpentine treated rabbits, as were thrombus size (assessed by visual scoring), dry weight of thrombi, and their fibrin content (derived by measuring 125I-fibrinogen incorporation). In addition, the fibrinogen concentration correlated significantly with size, weight, and fibrin content of thrombi when results from turpentine treated and control animals were pooled, suggesting that plasma fibrinogen concentration at the time of thrombus formation may strongly influence the extent of thrombosis. This effect could help explain observations of a "hypercoagulable state" after injury.