A PROSPECTIVE LONGITUDINAL-STUDY OF PLATELET ANGIOTENSIN-II RECEPTORSFOR THE PREDICTION OF PREECLAMPSIA

Objectives: We developed a simplified method using a relatively small volume of blood for the determination of platelet angiotensin II recep tors by saturation analysis and we evaluated its performance for the p rediction of preeclampsia. Design and methods: A platelet suspension w ith minimal contamination by leukocytes and erythrocytes is obtained b y centrifugation and washing. The platelet concentrate is incubated in a multi-well plate with increasing concentration of radiolabelled ang iotensin II in the presence or absence of an excess of unlabelled angi otensin II. Bound and free fractions are separated using an oil mixtur e. Maximum binding is determined by Scatchard plot. This method was co mpared with a previously reported method. Our method was prospectively evaluated in 801 women attending our institution for routine prenatal care. A specimen was obtained at each trimester of pregnancy whenever possible. Diagnosis of preeclampsia was done postnatally by an experi enced obstetrician. Results: The method showed acceptable correlation with a previously published method although a proportional bias of 2.1 was observed between the two methods. No differences in mean maximum binding were observed between normal and affected pregnancies at eithe r trimester. Even when the results were analyzed longitudinally, using the change in maximum binding between two trimesters for each patient , no significant increase could be documented in preeclamptic pregnanc ies. Conclusions: Platelet angiotensin II receptor measurement is not a clinically useful marker for the prediction of preeclampsia. Copyrig ht (C) 1998 The Canadian Society of Clinical Chemists.