Prostacyclin/thromboxane early changes in pregnancies that ate complicated by preeclampsia

OBJECTIVE: The purpose of this study was to examine 6-keto-prostaglandin F-1alpha and thromboxane B-2 plasma levels throughout normotensive and preeclamptic pregnancies and to analyze the predictive values of these quantifications for the detection of preeclampsia during the second trimester of pregnancy. STUDY DESIGN: Blood samples were collected from 30 healthy, nonpregnant women and at 4-week intervals from a cohort of nulliparous women who were recruited before 16 weeks of gestation. Preeclampsia developed in 26 patients; 52 normotensive control subjects were matched from the same cohort. The 6-ketoprostaglandin F-1alpha and thromboxane B-2 were assayed by radioimmunoassay. Trends were compared between pregnancy groups and with the nonpregnant women. Predictive values were determined with the second-trimester assessments. RESULTS: The 6-keto-prostaglandin F-1alpha/thromboxane B-2 ratio decreased throughout pregnancy in women with preeclampsia; there were no significant changes in normotensive women. We found higher thromboxane B2 levels within the group with preeclampsia during the first gestational trimester (preeclampsia, 188 17 pg/mL; control, 119 +/- 4.8 pg/mL [mean +/- SEM]; P =.001). During the third trimester, patients with preeclampsia had lower 6-keto-prostaglandin F-1alpha levels than did control subjects (preeclampsia, 191 +/- 9.8 pg/mL; control, 288 +/- 10 pg/mL; P =.001). The 6-keto-prostaglandin F-1alpha/thromboxane B-2 ratio was suitable to calculate predictive values; the best cutoff point and time interval were 30 and 22 to 26 weeks of gestation, respectively Sensitivity, specificity, and positive and negative predictive values were 88%, 97%, 69%, and 99%, respectively; the odds ratio was 14.6 (95% Cl, 6.9-30.4). CONCLUSION: The prostacyclin/thromboxane ratio favored vasoconstriction early in gestation in women in whom preeclampsia developed. A 6-keto-prostagland in F-1alpha/thromboxane B-2 ratio of less than or equal to3.0 at 22 to 26 weeks of gestation had a high predictive value for the development of preeclampsia.