Changes in Lp(a) lipoprotein and lipid levels after cessation of female sex hormone production and estrogen replacement therapy

Abstract

Objective: To investigate the serial changes in Lp(a) lipoprotein levels with the loss of female sex hormones by surgical menopause and with estrogen replacement therapy in the same women. Patients and Methods: Forty-four premenopausal women who underwent a transabdominal hysterectomy (TAH) because of benign gynecological disorders were divided into two groups: women who underwent a TAH and unilateral salpingo-oophorectomy (n=31) and women who underwent a TAH and bilateral salpingo-oophorectomy (n= 13). In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, 0.625 mg of conjugated equine estrogen was given daily 2 months after the operation. The levels of Lp(a) lipoprotein and lipids were measured before and at 2 and 4 months after the operation. Results: In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, the mean (±SD) concentration of Lp(a) lipoprotein was increased by 24.5% from 0.48±0.47 mmol/L (18.4±18.3 mg/dL) to 0.59±0.54 mmol/L (22.9±21.0 mg/dL) after 2 months(P<.05), and it was reduced by 30.6% to 0.41±0.51 mmol/L (15.9±20.1 mg/dL) (P<.005) with therapy with conjugated equine estrogen (Premarin). The Lp(a) lipoprotein levels were not changed in the group of women who underwent a TAH and unilateral salpingo-oophorectomy. In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, the high-density lipoprotein cholesterol level showed a trend of increase after 2 months from 1.45±0.48 mmol/L (56.1±18.5 mg/dL) to 1.58±0.39 mmol/L (61.2±15.1 mg/dL) without statistical significance, and it revealed a significant elevation to 1.76±0.43 mmol/L (68.2±16.8 mg/dL) with therapy with conjugated equine estrogen (Premarin) compared with that of the basal level (P<.05). Conclusions: The Lp(a) lipoprotein levels appear to be closely associated with female sex hormones. This association might play a pivotal role in postmenopausal increases of atherosclerotic diseases and cardioprotective effect of estrogen in postmenopausal women.