Platelet Angiotensin II Binding Sites and Early Detection of Preeclampsia

Abstract

In Brief Objective To determine if platelet angiotensin II binding density during the second or third trimester of pregnancy can be used as a marker for early detection of women who will develop preeclampsia. Methods We collected blood samples from 412 nulliparous pregnant women during their second or third trimesters. They were classified in four groups after delivery: noromtensive (n = 297), transient hypertensive (n = 54), preeclamptic (w = 39), and chronic hypertensive (n = 22). We also studied 35 nonpregnant women and 122 women in the peripartum period. The binding capacity of platelet angiotensin II receptors was analyzed in each patient. Results In normotensive pregnancies, there was a significant decrease in mean (± standard error of the mean [SEM]) platelet binding in the second trimester (1.6 ± 0.2 fmol/109 cells) compared with nonpregnant women (3.3 ± 0.7 fmol/109 cells). No statistical differences were observed in the mean (± SEM) number of platelet angiotensin II binding sites between the groups studied in the third trimester (normal: 1.7 ± 0.1 fmol/109 cells; transient hypertensive: 2.3 ± 0.4 fmol/109 cells; preeclamptic: 1.6 ± 0.4 fmol/109 cells, and chronic hypertensive: 1.6 ± 0.6 fmol/109 cells), nor were any significant differences found in second-trimester values. At cutoff levels providing identical sensitivities, angiotensin II binding showed significantly lower positive predictive values than mean arterial pressure (P < .05). With this study's sample size, we could have demonstrated an improvement in positive predictive values of 20% with a statistical power (1-β) of 90%. Conclusion The measurement of platelet angiotensin II receptor density cannot be recommended for the early detection of preeclampsia. Platelet angiotensin II receptor density does not predict later development of preeclampsia.