Increase in circulating levels of cardiac natriuretic peptides after hormone replacement therapy in postmenopausal women

The mechanisms that mediate the cardioprotective action of steroid hormones in postmenopausal women are poorly understood. To study the inter-relation ship between female steroid hormones and cardiac natriuretic peptides, plas ma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured in postmenopausal women, both before and after oestrog en replacement therapy. A total of 22 healthy postmenopausal women (mean ag e 51.9 +/- 4.6 years) were enrolled in the study; all had been postmenopaus al for at least I year and all reported climacteric symptoms accompanied by increased levels of follicle-stimulating hormone (> 30 m-i.u./ml) and lute inizing hormone (> 20 m-i.u./ml), and a reduction in oestradiol (< 25 pg/ml ). All women were given hormone replacement therapy with transdermal oestra diol, either patch (50 mug/24 h) or gel (1 mg/day), cyclically combined wit h oral dihydrogesterone (10 mg/day for 12 days/month, on days 19-30 of the month). ANP and BNP were measured directly in plasma samples with specific and sensitive immunoradiometric assays before and after hormone replacement therapy (transdermal oestradiol combined with oral dihydrogesterone). Body weight, arterial blood pressure and echocardiographic examination values d id not change after hormone replacement therapy. As expected, serum oestrad iol increased significantly and gonadotropins decreased as an effect of the hormone replacement therapy. On average, both ANP and BNP had increased si gnificantly after 3 months of hormone replacement therapy [ANP: before trea tment, 17.6 +/- 9.6 pg/ml; after, 23.6 +/- 5.6 pg/ml (P = 0.0173); BNP: bef ore treatment, 12.6 +/- 10.2 pg/ml; after, 19.8 +/- 14.0 pg/ml (P < 0.0001) ]. Our study indicates that hormone replacement therapy for a period of 3 m onths induces a rise in the circulating levels of cardiac natriuretic hormo nes in postmenopausal women. Our data also suggest the working hypothesis t hat cardiac natriuretic peptides may play an important role in mediating th e cardioprotective effects of female steroid sex hormones in women througho ut life.