Lack of thrombopoietin potentiation of platelet collagen activation in the first trimester is associated with preeclampsia

To determine whether a difference exists in platelet reactivity to collagen and potentiation by thrombopoietin (TPO) between preeclamptic and non-preeclamptic patients, 187 first trimester pregnant patients were prospectively followed through pregnancy. Citrated blood, drawn at first (<14 weeks estimated gestational age) and third trimesters (>28 weeks), when patients were admitted for delivery, and 4-6 weeks postpartum, was assayed by a Whole Blood Impedance Aggregometer measuring platelet activation by 0.4 mug/ml collagen, +/-10 ng/ml TPO. There was no significant difference in 1st trimester platelet collagen activation by unpaired t-test between groups. Significant TPO potentiation of collagen activation (P<0.05, paired t-test) was observed in non-preeclamptic patients at the first and third trimesters. In contrast, preeclamptic patients' platelets show no significant (P>0.8, paired t-test) TPO potentiation at any time. While the mechanism for this difference in thrombopoietin potentiation of platelet activation by collagen as early as the first trimester is unknown, it may be one of the initiating events in this syndrome.