Serum lipoprotein and apolipoprotein changes during treatment with a contraceptive vaginal ring containing...

Contraceptive vaginal rings containing estradiol and levonorgestrel were used by 22 women during 219 cycles. The estrogenicity was low and the daily dose of levonorgestrel was about 290 micrograms. The triglyceride and cholesterol concentrations decreased in whole serum and, to varying degrees, in the different lipoprotein classes. The most consistent change was a 25% (p less than 0.001) reduction in the cholesterol content of the high-density lipoprotein (HDL) fraction. The cholesterol concentration in low-density lipoprotein decreased by 11% after the first 3 months, but increased during the ensuing 9 months of treatment to regain pretreatment level. Percentage-wise, the apolipoprotein B and A-I concentrations, determined by rocket immunoelectrophoresis, were less affected than the LDL- and HDL-cholesterol concentrations. The composition of the LDL and HDL particles seemed thus to alter during the treatment. The pronounced effect on the HDL levels seen is consistent with earlier findings of a dose-dependent, androgenic effect of gestagens derived from 19-nortestosterone. However, the low basal level of LDL and its further decrement during treatment alleviate the supposedly unfavorable effect of HDL reduction from the atherogenic point of view.