Platelet activation in pregnancy-induced hypertension

Background: Although excess platelet activation, as indicated by increased plasma beta thromboglobulin (β-TG), has been shown in pregnancy-induced hypertension (PIH), platelet adhesion, platelet morphology and a comparison of platelet and soluble (plasma) levels of the adhesion molecules P-selectin (pPsel and sPsel, respectively) have not been studied. Methods: We conducted a cross-sectional study of 35 consecutive women with PIH (age 31±6 years), 31 consecutive women with normotensive pregnancies (age 29±5 years) and 30 normotensive non pregnant women (age 30±5 years). Platelet adhesion was studied in vitro by binding to fibrinogen-coated microwells, platelet morphology [mass and volume by flow cytometry], whole-platelet P-selectin (pPsel) by ELISA of the lysate of 2×10⁸ cells, and the plasma markers soluble P-selectin (sP-sel) and β-TG, by ELISA. Results: The women with PIH had significantly raised sPsel, pPsel and (as expected) β-TG (all p<0.05), when compared to the normotensive pregnant women and controls. However, in PIH platelet adhesion was similar to that in the normotensive pregnancy, but still higher than the normal controls (p<0.001). There was no difference among the three groups with respect to platelet mass and volume. pPsel and platelet adhesion correlated with gestational age and with systolic and diastolic blood pressure (all p<0.05). Conclusions: Increased platelet activation and adhesion develop during normal pregnancy, with some indices being further altered in PIH.