Changes in the plasma levels of protein C system parameters in pregnancy.

Resistance to activated protein C (APC) is a condition that leads to a hypercoagulative state with an increased risk for venous thrombosis. The aim of this study was to test the functionality of the protein C system in normal and complicated pregnancies and APC resistance. A total of 131 patients were tested, including pregnant women with normal and complicated pregnancies at different periods, e.g. from weeks 1 to 20, 21 to 30 and 31 to 38 of gestation. The following hemostatic parameters were determined: protein S, protein C, protein C Global and protein C APC sensitivity. Commercial "Behring" tests were used to determine the parameters of hemostasis. The values for protein C activity were within normal limits. Protein S values were below the lower limits. Significantly lower PC-NR (protein C normalized ratio) and APC-NR (activated protein C normalized ratio) values were found in all three of the gestation periods in pregnant women with a history of repeated miscarriages and hypertension in relation to pregnant women with normal pregnancies. In order to assess the diagnostic accuracy of investigated hemostatic parameters as markers of prethrombotic changes in pregnant women, the obtained values of investigated hemostatic parameters were evaluated by ROC analysis. PC-NR and APC-NR showed satisfactory diagnostic accuracy as markers of prethrombotic changes in pregnant women: more precisely, they were found to be good indicators of resistance to activated protein C in pregnancy.