Summary. Levels of activated factor XII (FXIIa) and VII (FVIIa) were determined in 100 women with uneventful pregnancies. Samples were divided into five study intervals: three during pregnancy, one at delivery and one 3 d postpartum.The median (range) for FXIIa levels were 3·4 ng/ml (1·2-9·1) from 11 to 20 weeks, 4·6 ng/ml (1·4-15·2) from 21 to 30 weeks, 5·4 ng/ml (1·9-14·3) from 31st week to delivery, 5·2 (1·3-11·4) at delivery and 4·3 (1·8-8·5) ng/ ml in the postpartum sample. For FVIIa the median and range levels for the five periods were 4·9 (1·7-77·3), 7·2 (2·5-80·4), 11·1 (2·9-90·6), 12·0 (3·1-64·1) and 8·2 (4·0-23·5) ng/ml. Although the increase of FVIIa was higher than that of FXIIa during pregnancy, the overall changes of FXIIa and FVIIa were highly correlated (P < 0·0001). At each time period the changes of FVIIa correlated with FVII:C which was not the case with FVII:Ag. These data indicate that during pregnancy both the contact phase and extrinsic pathway are activated.Keywords: activated factor VII, factor VII antigen, factor VII activity, activated factor XII, pregnancy.Activation of coagulation can be mediated by the extrinsic or intrinsic pathways. The first enzyme of the extrinsic pathway is factor VIIa (FVIIa), which is the enzymatically active form of the zymogen factor VII. Activated factor XII (FXIIa), on the other hand, is the central enzyme of the contact phase. Until recently, levels of FVIIa and FXIIa were estimated by indirect methods, but new assays have recently been developed. For FVIIa a clotting assay using a soluble mutant of tissue factor (Morrisey et al, 1993;Ford et al, 1996) and an ELISA are now available (Philippou et al, 1997). These assays, which enable direct measurement of FVIIa in plasma, are apparently free of interference from the FVII zymogen (Wildgoose et al, 1992; Morrisey et al, 1993; Eichinger et al, 1997;Philippou et al, 1997). For FXIIa an immunoassay is now also available (Boisclair et al, 1993); it measures FXIIa directly in plasma with minimal crossreaction with the zymogen factor XII.Due to the many changes observed in haemostatic parameters, pregnancy is a particular subject of interest in understanding the activation of coagulation in a physiological state. Two preliminary reports have indicated either an increase of FVIIa (Morrissey et al, 1993) or of FXIIa (Coppolla et al, 1996) in normal pregnancies. Since no longitudinal studies on a large group of normal pregnant women have been performed, the aim of our study was to extend these preliminary observations by measuring systematically during pregnancy, at delivery and in the postpartum both FVIIa and FXIIa, and by comparing their levels with those of FVII clotting activity, FVII antigen and fibrinogen levels. PATIENTS AND METHODSThe study protocol was approved by the Ethical Committee of the University of Geneva Hospital. 100 women with uneventful pregnancies were included in the final analysis; 21 women were not included due to gestational hypertension, pre-eclampsia, diabetes mellitus and intrauterine...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.