Postmenopausal hormone replacement therapy with Tibolone decreases serum lipoprotein(a)

Lipoprotein(a) is a cholesterol-rich plasma lipoprotein consisting of LDL and apolipoprotein(a). Apolipoprotein(a) shows structural similarity with plasminogen and thus may interfere with thrombogenesis. Lipoprotein(a) has been shown to be a strong independent risk factor for coronary heart disease. So far no drug or diet is known to have prominent effects on the serum levels of lipoprotein(a). In the present study we found a highly significant decrease (in the order of 26%) of lipoprotein(a) in 28 women treated for 6 months with Tibolone, compared with an age-matched healthy control group. Tibolone is a synthetic steroid with gestagenic and weak androgenic and oestrogenic properties, which shows no stimulation of the endometrium. Tibolone also produced a decrease in HDL-cholesterol of 23% (p < 0.001), a decrease in apolipoprotein A-I of 14% (p < 0.001) and an increase in apolipoprotein B of 17% (p < 0.001), whereas the control group showed no significant changes in these quantities. Tibolone in a daily dose of 2.5 mg is at present the only complete postmenopausal hormone replacement therapy that shows a significant inhibiting influence on serum levels of lipoprotein(a). Its effect on lipoprotein(a) might counterbalance, at least to some extent, the theoretical adverse effect on the other lipoprotein risk factors.