The effects of oestrogen administration on the plasma free protein S and C4b-binding protein

Abstract

This study was undertaken to evaluate the effects of oestrogen administration (low dose as an oral contraceptive or higher dose as a hormone replacement therapy) on the levels of plasma free protein S and C4b-binding protein. The participants were 59 women aged 18-49 years, divided into 2 groups: A and B. Group A was composed of 22 post-menopausal women on a hormonal replacement therapy programme (HRT) consisting of 2 mgs daily oestradiol valerate for 21 days. Group B was divided into subgroup B1: 18 women who had been on oral contraceptive for at least one year and subgroup B2 (control): 17 women who were not pregnant and not taking any oral contraceptive. In this study were also included two young women who both suffered from severe thromboembolic disease a few months after initiation of oral contraceptive. The first was 25 years old, with congenital moderately decreased prekallikrein (activity and antigen 40% and 45% respectively) and the second was a 21 year-old woman with congenital moderately decreased plasminogen activity and antigen 45%). In both cases, family members with similarly reduced levels of prekallikrein (PK) and plasminogen (PLG) respectively were free from any thromboembolic disease and had normal protein S levels. In Group A, 22 women at the end of the first cycle of treatment, had lower levels of free protein S (p less than 0.001) than before the initiation of HRT. In subgroup B1, the levels of free protein S were found to be significantly lower than in subgroup B2 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: This study was undertaken to evaluate the effects of estrogen administration (low dose as an oral contraceptive [OC[ or higher dose as hormone replacement therapy (HRT) on the levels of plasma free protein S and C4b-binding protein. The participants were 59 women ages 18-49 years, divided into 2 groups. Group A was composed of 22 postmenopausal women on an HRT program consisting of 2 mg daily estradiol valerate for 21 days. Group B was divided into subgroup B1--18 women who had been on OCs for at least 1 year--and subgroup B2--a control group of 17 women who were not pregnant and not taking any OCs. In this study were also included 2 young women who both suffered from severe thromboembolic disease a few months after initiation of OCs. The 1st was 25 years old, with congenital moderately decreased prekallikrein (PK); (activity and antigen 40% and 45%, respectively) and the 2nd was a 21-year old woman with congenital moderately decreased plasminogen (PLG) activity and antigen 45%. In both cases, family members with similarly reduced levels of PK and PLG respectively were free from any thromboembolic disease and had normal protein S levels. In Group A, 22 women at the end of the 1st cycle of treatment had lower levels of free protein S (p0.001) than before HRT initiation. In subgroup B1, the levels of free protein S were found to be significantly lower than in subgroup B2 (p0.001). Although the C4b-binding protein was 20% lower in subgroup B1 than in the other subgroup, this does not represent a significant difference. Since an association between OC use and incidence of venous thromboembolism without predisposition to thrombosis has been consistently observed in case-control and cohort studies, the authors conclude that estrogen reduces free protein S in both group A and subgroup B1; i.e., the group receiving higher dosages as an HRT for a period of 21 days, and the subgroup B1 receiving low doses as an OC over 12 months, whose mild deficiency in a factor may predispose the thrombosis heretofore dormant.