Elimination of antithrombin III concentrate in healthy pregnant and preeclamptic women with an acquired antithrombin III deficiency.

The activity elimination half-life of heat-treated antithrombin III (AT III) concentrate was studied in 5 healthy pregnant and 5 preeclamptic women with a documented AT III deficiency. Healthy pregnant women received 1500 units over 20 minutes. Serial blood specimens were obtained over the next 12 hours. The mean (+/- SEM) activity elimination half-life of AT III was 29.4h +/- 3.4h. Preeclamptic subjects had a mean baseline AT III activity of 70.5 +/- 2% (range 61 to 75%). Their activity eliminator half-life after 3000 units of AT III concentrate was 8.5 +/- 1.2h. There was a direct relationship between the pre-concentrate AT III activity level and the AT III activity elimination half-life (r = 0.79, p = 0.01) for all subjects. Based upon parameters calculated from the first infusion, the AT III activity of preeclamptic subjects was maintained by a constant infusion at approximately 100% for 96h. At the conclusion of the infusion, the activity elimination half-life was again measured. A dramatic increase in the activity elimination half-life was demonstrated (433.6h). We conclude that the activity elimination half-life of AT III concentrate is increased during normal pregnancy and further increased in preeclamptic women with an acquired deficiency.