title: Unopposed estrogen increases total plasma factor VII, but not active factor VII--a short-term placebo-controlled study in healthy postmenopausal women.
abstract: Estrogen therapy may increase the risk of arterial thromboembolism, at least in the short term. In a randomized, double-blind and placebo-controlled study in 25 healthy postmenopausal women (52.5 +/- 2.8 years), we therefore examined the short-term effect of unopposed estrogen on the fasting and fat-load-stimulated plasma levels of total factor VII versus active factor VII. Plasma total factor VII was measured by use of a chromogenic assay; plasma active FVII by a recently developed method using truncated tissue factor. As compared to placebo, 8 weeks of oral 17beta-estradiol (2 mg daily) increased the mean fasting and postprandial plasma levels of total factor VII by 17 and 21% points, respectively (both P < 0.01 ), but did not affect the fasting and/or postprandial plasma levels of active factor VII (mean change both 0.05 ng/mL; P > 0.35). Furthermore, the change in the fasting level of total factor VII after therapy was not associated with the change in the fasting level of active factor VII (r = 0.27; P = 0.21). These findings argue against the idea that elevated levels of total factor VII underlie an increased risk of arterial thromboembolism in postmenopausal women using unopposed estrogen replacement.
authors.affiliation: Department of Endocrinology, Research Institute for Endocrinology, Reproduction and Metabolism, University Hospital Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: G W
authors.initials: GW
authors.lastname: de Valk-de Roo
authors.forename: C D
authors.initials: CD
authors.lastname: Stehouwer
authors.forename: J J
authors.initials: JJ
authors.lastname: Emeis
authors.forename: A
authors.initials: A
authors.lastname: Nicolaas-Merkus
authors.forename: C
authors.initials: C
authors.lastname: Netelenbos
mesh_terms: D004311:Double-Blind Method; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005167:Factor VII / Q000187:drug effects* / Q000378:metabolism; D015942:Factor VIIa / Q000187:drug effects* / Q000378:metabolism; D005215:Fasting; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D019518:Postprandial Period; D011446:Prospective Studies; D044465:White People
chemical_list: D004967:Estrogens; D005167:Factor VII; D015942:Factor VIIa