title: Decrease in protein C inhibitor activity and acquired APC resistance during normal pregnancy.
abstract: BACKGROUND
  Since protein C inhibitor (PCI) inhibits activated protein C (APC) and a number of proteases, one would expect lower concentrations of PCI in a hypercoagulable state due to increased consumption of the inhibitor. Normal pregnancy is associated with a state of activated hemostasis, where response to APC is depressed. We aimed to study whether PCI function varies during normal pregnancy, and assess the relationship between this inhibitor and acquired APC resistance.
  
  
  METHODS
  PCI activity in plasma was tested during pregnancy and postpartum in 28 healthy pregnant women without factor V Leiden Arg(506) - Gln mutation and in 14 non-pregnant female controls. The PCI levels determined in the present study was compared to the APC ratio (APC-r), we investigated previously, in the same samples.
  
  
  RESULTS
  The levels of PCI in the pregnant group, as compared to that in the control group (4.74 +/- 0.48), gradually decreased from the first to the third trimester, i.e., 3.30 +/- 1.31 microg/mL in week 12 (p < 0.001), 2.66 +/- 1.44 microg/mL in week 20 (p < 0.001), 1.92 +/- 1.18 microg/mL in week 28 (p < 0.001), 1.30 +/- 0.94 microg/mL in week 32 (p < 0.001) and 1.49 +/- 1.12 microg/mL in week 37 (p < 0.001). After delivery, they rose to 5.02 +/- 1.93 microg/mL, similar to that in the controls (p > 0.05). The values of APC-r showed the same tendency during gestation and postpartum.
  
  
  CONCLUSIONS
  With advance of normal pregnancy, decreasing PCI function corresponds to increasing APC resistance, probably due to that activated hemostasis acts as a link connecting the two variables.
authors.affiliation: Department of Laboratory Medicine/Coagulation Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Shu
authors.forename: M
authors.initials: M
authors.lastname: Wramsby
authors.forename: M
authors.initials: M
authors.lastname: Bokarewa
authors.forename: M
authors.initials: M
authors.lastname: Blombäck
authors.forename: K
authors.initials: K
authors.lastname: Bremme
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood*; D000328:Adult; D005260:Female; D006801:Humans; D049590:Postpartum Period / Q000097:blood; D011247:Pregnancy / Q000097:blood*; D018046:Protein C Inhibitor / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018046:Protein C Inhibitor