Lp(a) levels and antiestrogen antibodies in women with and without thrombosis in the course of oral contraception

Abstract

Several reports have shown that lipoprotein(a) is associated with ischemic diseases. Two characteristics might explain this association. Firstly, Lp(a) is an LDL-like lipoprotein which may be implicated in the atherosclerotic process and secondly, Lp(a) possesses an additional apolipoprotein(a) whose structure is close to that of plasminogen and might confer to the molecule prothrombotic properties. It seemed of interest to see whether Lp(a) was a risk factor in oral contraceptive users with thrombotic complications, a group of young women with presumably little or no atherosclerosis. Three groups of women were compared: 25 of them served as controls and did not use oral contraceptives (OC) (group 1); 25 women were healthy current users of OC (group 2); 35 women suffered thrombotic complications in the course of OC (group 3). Mean levels of Lp(a), estimated by RID, were not found to be significantly different in the 3 groups: 19 ± 18, 20 ± 23 and 16 ± 22 mg/dl, respectively. Levels above 30 mg/dl were similarly distributed. Among the other risk factors studied, antiestrogen antibodies were absent in group 1, present in 24% of group 2 and 71.4% of group 3 ( P < 0.01). Serum cholesterol levels were similar in the 3 groups: 209 ± 33, 220 ± 41, 213 ± 45 mg/dl respectively. Mean serum triglyceride levels were higher in group 2 than in group 1 (61 ± 18 and 83 ± 32, P < 0.01), and higher in group 3 than in group 2 (116 ± 66 and 83 ± 32, P < 0.05). Smoking was more frequently observed in the groups of thrombotic complications (62.8%) than in healthy OC users (20%, P < 0.05). It is concluded that, while antiestrogen antibodies, smoking and increased triglyceride levels are associated factors in the thrombotic complications of OC, Lp(a) does not appear to be a risk factor in OC users without atherosclerosis.