The procoagulant effects of factor V Leiden may be balanced against decreased levels of factor V and do not reflect in vivo thrombin formation in newborns

Thrombosis and Haemostasis
Satu HyytiäinenJari Petäjä

Abstract

Thrombin regulation in newborns remains incompletely understood. We studied tissue factor-initiated thrombin formation in cord plasma in vitro, and the effects of Factor V(Leiden) (FVL) heterozygosity on thrombin regulation both in vitro and in vivo in newborns. Pregnant women with known thrombophilia (n=27) were enrolled in the study. Cord blood and venous blood at the age of 14 days were collected from 11 FVL heterozygous newborns (FVL-positive) and from 16 FVL-negative newborns. Prothrombin fragment F1 +2 and coagulation factors were measured. Tissue factor-initiated thrombin formation was studied in cord platelet-poor plasma (PPP) of FVL-negative and -positive newborns, and in both PPP and platelet-rich plasma (PRP) of healthy controls. The endogenous thrombin potential (ETP) in cord PPP or PRP was approximately 60% of that in adult plasma, while thrombin formation started approximately 55% and approximately 40% earlier in cord PPP and PRP, respectively. Further, in FVL-positive newborns thrombin formation started significantly earlier than in FVL-negative newborns. Exogenous activated protein C (APC) decreased ETP significantly more in cord than in adult PRP. In FVL-negative cord plasma 5 nM APC decreased ETP by 17.4+/-3.5...Continue Reading

Citations

Jul 13, 2007·Journal of Perinatology : Official Journal of the California Perinatal Association·R TurebyluR M Ryan
Jun 21, 2011·Haemophilia : the Official Journal of the World Federation of Hemophilia·U Wartiovaara-KauttoR Lassila
Dec 23, 2010·Hypertension in Pregnancy : Official Journal of the International Society for the Study of Hypertension in Pregnancy·Yu XiongXiao-Tian Li

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