The imbalance between thromboxane and prostacyclin in preeclampsia is associated with an imbalance between lipid peroxides and vitamin E in maternal blood

Abstract

Preeclampsia is associated with an imbalance between thromboxane and prostacyclin. The cause of the imbalance is unknown. Preeclampsia sera contain cytotoxic factors that can damage endothelial cells. Lipid peroxides can damage cell membranes, so elevated levels in the mother's blood could be related to endothelial cell injury and decreased prostacyclin in preeclampsia. This study determined maternal plasma levels of thromboxane and prostacyclin and serum levels of lipid peroxides and vitamin E in women with normal pregnancy (n = 12), mild preeclampsia (n = 16), and severe preeclampsia (n = 19) between 36 and 40 weeks' gestation. In normal pregnancy the ratio of thromboxane to prostacyclin (0.63) favored prostacyclin, and the ratio of lipid peroxides to vitamin E (0.43) favored vitamin E. Prostacyclin was significantly decreased in both mild and severe preeclampsia. Thromboxane was not increased in mild preeclampsia but was significantly increased in severe preeclampsia. The ratio of thromboxane to prostacyclin was increased in mild preeclampsia (0. 77) and greatly increased in severe preeclampsia (1.94). Lipid peroxides were significantly increased in mild preeclampsia and increased further in severe preeclampsia. Vitamin E levels were unaltered in mild preeclampsia but significantly decreased in severe preeclampsia. The ratio of lipid peroxides to vitamin E was increased in mild (0.52) and greatly increased in severe (1.09) preeclampsia. We concluded the following: (1) Maternal plasma prostacyclin is decreased in both mild and severe preeclampsia, but thromboxane is increased only in severe cases. (2) Lipid peroxides are significantly increased in both mild and severe preeclampsia and vitamin E is significantly decreased in severe preeclampsia. We speculate that this imbalance could result in endothelial and platelet cell damage and in decreased prostacyclin and increased thromboxane synthesis. (3) Preeclampsia is associated with an imbalance not only between thromboxane and prostacyclin but also between lipid peroxides and vitamin E in maternal blood. The imbalances progressively favor thromboxane and lipid peroxides with the increasing severity of preeclampsia, which is consistent with the clinical symptoms of this disorder. (AM J OBSTET GYNECOL 1991;165:1695-1700.)