Effect of hormone replacement therapy on tissue factor activity, C-reactive protein, and the tissue factor pathway inhibitor

Abstract

W have previously observed that hormone replacement therapy (HRT) significantly increased tissue factor (TF) activity in healthy women1 and tended to increase prothrombin fragment 1 2 levels in 20 hypertensive and/or overweight postmenopausal women.2 However, we did not measure other indexes of coagulation activation or inhibition, nor did we measure C-reactive protein (CRP), which in experimental preparations stimulates the synthesis and release of the coagulation activator TF.3 TF pathway inhibitor (TFPI) may interact with TF to maintain homeostasis.4,5 Thus, this study examines (1) whether HRT increases TF activity, which may facilitate thrombin formation in hypertensive and/or overweight postmenopausal women, and (2) whether HRT-induced TF activity is associated with changes in CRP or TFPI that might provide mechanistic insight. • • • Thirty postmenopausal women (mean SD 59 6 years) participated in this study. Inclusion criteria have been previously reported.2 Eight, 8, and 14 women were overweight, hypertensive, and both, respectively. Seven of 22 were obese. Mean body mass index was 28.7 3.4. We treated hypertensive women with a low salt diet and/or diuretics (hydrochlorothiazide or furosemide) alone to avoid drug effects on hemostasis. This study was randomized, double-blind, and crossover in design. Study participants received micronized progesterone (MP) 100 mg or medroxyprogesterone acetate (MPA) 2.5 mg with conjugated equine estrogen (CEE) 0.625 mg daily for 2 months with the second treatment period initiated upon completion of the first treatment period. The study was approved by the Gil Hospital institute review board and all participants gave written, informed consent. Assays for hemostasis were performed as previously described.6,7Blood samples for laboratory assays were obtained from an antecubital vein after an overnight fast, before and at the end of treatment. Because of the circadian variation of fibrinolytic activity, blood collection was restricted to the hours of 8 to 9 A.M. We measured parameters of coagulation system activation. Prothrombin fragment 1 2 and thrombin-antithrombin complexes were measured by enzyme-linked immunosorbent assays (ELISA) (Behring Diagnostics Inc., San Jose, California). TF and TFPI antigen and activity were measured in duplicate by ELISA and actichrome assays (American Diagnostica, Greenwich, Connecticut). In all patients, serum was collected for the measurement of CRP levels. CRP levels were determined with an immunonephelometry system according to methods described by the manufacturer (Rate nephelometry; IMMAGE, Beckman Coulter, Brea, California). The measurement range was 0.1 to 98 mg/dl. All samples from the same patient (batch samples) were measured in blinded pairs with the same ELISA kit to minimize run-to-run variability. The interand intraassay coefficients of variation were 8%. Data are expressed as mean SEM or median (range 25% to 75%). After testing data for normality, we used Student’s paired t test or the Wilcoxon signed-rank test to compare values at baseline and after each therapy, as reported in Table 1. We assumed that the second baseline after the washout would not be different from the first baseline, because we saw no carryover effect of CEE and progestagen after 6 weeks in our previous studies.6,8 Thus, we decided on a treatment period of 2 months without washout. The effects of the 2 therapies on markers of hemostasis relative to baseline values were analyzed by 1-way repeated measures analysis of variance or Friedman’s repeated analysis of variance on ranks. After demonstration of significant differences among therapies by analysis of variance, post hoc comparisons between treatment pairs were made using the Student-Newman-Keuls multiple comparison procedures. Pearson’s correlation coefficient analysis was used to assess associations between measured parameters. In light of the multiple comparisons generated by the exploratory nature of this study, a p value 0.001 (rather than 0.05) was used to indicate statistical significance. There were no carryover effects from the initial treatment periods to the next treatment period. The effects of therapies on hemostasis are shown in Table 1. CEE MP and CEE MPA therapies tended to increase CRP levels from baseline values (p 0.107 by analysis of variance). Both therapies significantly decreased TF antigen but increased TF activity from From the Departments of Cardiology, Clinical Pathology, and Preventive Medicine (Biostatistics), Gachon Medical School, Incheon, Korea. This study was supported by grants (2000-1-20500-1) from the Basic Research Program, Korea Science and Engineering Foundation, Taejeon, Korea. Dr. Koh’s address: Vascular Medicine and Atherosclerosis Unit, Cardiology, Gil Heart Center, Gachon Medical School, 1198 Kuwol-dong, Namdong-gu, Incheon, Korea 405-760. E-mail: kwangk@ghil.com. Manuscript received July 15, 2002; revised manuscript received and accepted September 19, 2002.