PLATELET ANGIOTENSIN-II BINDING-SITES AND EARLY DETECTION OF PREECLAMPSIA

Objective: To determine if platelet angiotensin II binding density dur ing 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: normotensive (n = 297), transient hypertensive (n = 54 ), preeclamptic (n = 39), and chronic hypertensive (n = 22). We also s tudied 35 nonpregnant women and 122 women in the peripartum period. Th e binding capacity of platelet angiotensin II receptors was analyzed i n each patient. Results: In normotensive pregnancies, there was a sign ificant decrease in mean (+/- standard error of the mean [SEM]) platel et binding in the second trimester (1.6 +/- 0.2 fmol/10(9) cells) comp ared with nonpregnant women (3.3 +/- 0.7 fmol/10(9) cells). No statist ical differences were observed in the mean (+/- SEM) number of platele t angiotensin II binding sites between the groups studied in the third trimester (normal: 1.7 +/- 0.1 fmol/10(9) cells; transient hypertensi ve: 2.3 +/- 0.4 fmol/10(9) cells; preeclamptic: 1.6 +/- 0.4 fmol/10(9) cells, and chronic hypertensive: 1.6 +/- 0.6 fmol/10(9) cells), nor w ere any significant differences found in second-trimester values. At c utoff levels providing identical sensitivities, angiotensin II binding showed significantly lower positive predictive values than mean arter ial pressure (P < .05). With this study's sample size, we could have d emonstrated an improvement in positive predictive values of 20% with a statistical power (1-beta) of 90%. Conclusion: The measurement of pla telet angiotensin II receptor density cannot be recommended for the ea rly detection of preeclampsia. (C) 1998 by The American College of Obs tetricians and Gynecologists.