Contact activation factors in plasma from women on estrogen replacement therapy after ovariohysterectomy

The plasma levels of factor XII, prekallikrein, factor XI, and high molecul ar weight kininogen were studied in women with bilateral oophorectomy and h ysterectomy who received hormone replacement therapy with a 2 mg daily dose of estradiol valerate. Also plasminogen activator activity was investigate d. The observations made provide support for the assumption that the low do ses of estrogen used in hormone replacement therapy do not significantly af fect the levels of contact activation or fibrinolytic factors in plasma. Pl asma obtained from young, healthy women was used as a standard reference ma terial. Significantly higher levels of factor XII and prekallikrein were re gistered in functional tests in the ectomized women than in the reference m aterial, an increase not observed in the immunological assays. These observ ations are discussed in light of recently published data from our laborator y on an increase in the measured level of factor XII obtained upon the remo val of Ige before assay. Also a marked increase in urokinase activity was r egistered in the ectomized women. The high levels of factor XII, prekallikr ein, and urokinase, as compared with the reference material, seemed to be a ge dependent, being also observed in a group of naturally postmenopausal wo men. (C) 1999 Elsevier Science Ltd. All rights reserved.