Can the laboratory assay of protein C activity assist in monitoring the hemostatic function in pre-eclampsia?

Published reports do not agree about whether protein C activity is non-significantly changed or decreased in a hypercoagulable state induced by pre-eclampsia without hemolysis-elevated liver enzyme/low platelet (HELLP) syndrome. In order to assess the relationship between this anticoagulant and enhanced hemostasis, levels of protein C activity, thrombin-antithrombin complexes, soluble fibrin, fibrin D-dimers and antithrombin were determined in 30 pre-eclampsia patients without the HELLP syndrome, in 22 normal pregnant women in gestational weeks 30-35, and in 13 non-pregnant controls. Levels of thrombin-antithrombin complexes, soluble fibrin and D-dimers increased (P < 0.05) whereas antithrombin decreased (P < 0.05) in patients with pre-eclampsia, compared with normal pregnant women. Levels of protein C did not differ significantly between patients with pre-eclampsia, normal pregnant women and controls (P > 0.05). The 5th and 95th percentiles of protein C levels in normal pregnant women were 0.53 and 1.30 U/ml, respectively; levels between these two values could be considered physiological. When the pre-eclampsia patients were subdivided according to these percentiles, none belonged to the subgroup with protein C < or = 5th percentile; 23% (seven of 30) fell into the subgroup with protein C > or = 95th percentile. Elevated levels of hypercoagulation markers were shown in the groups whose protein C fell within 5th-95th or > or = 95th percentiles (P < 0.05), compared with normal pregnant women. Concentrations of protein C and thrombin-antithrombin complex were significantly correlated (r = 0.69, P > 0.05) in patients with pre-eclampsia. In summary, in subjects with pre-eclampsia without the HELLP syndrome, protein C activity may be similar to that in normal pregnant women. However, such a 'physiological' anticoagulant level in association with the enhanced thrombin generation and fibrin formation does not necessarily reflect a physiological capability of coagulation. Thus, assays of protein C activity might not always assist in monitoring the hemostatic function during pre-eclamptic pregnancy.