Current Generation Oral Contraceptive Pills and Hypercoagulability: A Pilot Study.
Soumya Pandey, Carolyn M Chesney. University of Tennessee Health Sciences Center, Memphis; Baptist Memorial Hospital- Memphis, Memphis, TN; Trumbull Laboratories, Memphis, TN
Background: Despite several changes in their formulations, the relative risk of Oral Contraceptive Pills (OCPs) related adverse effects has only come down from 11.0 to 4.4 and the current generations OCPs are not completely risk free. Previous studies have implicated both thrombin generation and platelet activation as underlying mechanisms for the adverse effects observed in the older generation OCPs. The purpose of this study was to reassess the effect of current generation OCPs on platelet activation and thrombin generation using newer and more sensitive techniques.
Design: The study was conducted on twenty healthy women 18-35 years of age taking OCPs and their twenty age matched controls. For detecting platelet activation the following tests were done: (1) Flow cytometric analysis for platelet monocyte aggregates: Whole blood flow cytometry is one of the new techniques for measuring platelet function and activation in their native milieu with minimal artificial stimulation. The following antibodies were used CD45 PerCP, CD14 PE and CD41a FITC. (2) Plasma platelet factor 4 (PF4) ELISA was used for quantitative determination of PF4 in plasma. Prothrombin fragment 1+2 (F1+2) enzyme immunoassay was used as a marker for thrombin generation. F1+2 is a peptide generated during the conversion of prothrombin to thrombin and bears a 1:1 stoichiometric relation to the generated thrombin.
Results: There were no statistically significant differences between the two subject groups (on OCPs vs. control group). The following results (mean ± SEM) were found in the OCP group vs. control group: platelet monocyte aggregates 23.97±0.86% vs. 21.87±0.79% (P=.079); PF4 1.05±0.20 ng/mL vs. 1.13±0.11 (P=0.740) and F1+2 185.1±11.02 pmol/L vs. 197.25±10.69 (P=0.448). There were no significant differences in platelet count, mean platelet volume or monocyte count between the two groups. There were no trends with age of subjects or the duration and type of OCPs.
Conclusions: This study examines the new methodology (flow cytometric analysis for platelet monocyte aggregates) for detection of platelet activation along with the already established marker PF4. Even though sensitive techniques were used in the study, hypercoagulable state was not detected in subjects on OCPs. However, since this study was done on only twenty subjects, further work needs to be done on a larger number of subjects to further evaluate the safety of OCPs.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 176, Tuesday Afternoon