Effects of Serum Estradiol on Proprotein Convertase Subtilisin/Kexin Type 9 Levels and Lipid Profiles in Women Undergoing In Vitro Fertilization

The mechanisms underlying the impact of estradiol (E2) on low-density lipoprotein cholesterol (LDL-C) levels are not completely understood, although a role for proprotein convertase subtilisin/kexin type 9 (PCSK9) has been proposed. We aimed to investigate the association between levels of E2, PCSK9, and lipid parameters in premenopausal women undergoing in vitro fertilization (IVF). Healthy women undergoing IVF in the Department of Obstetrics and Gynecology of the University General Hospital of Ioannina were recruited. Their levels of E2, PCSK9, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), LDL-C, and triglycerides (TGs) were measured 10 days after ovarian depression (E2min) and 7 days after ovarian stimulation (E2max). We included 34 consecutive women of median age 38 (interquartile range 26-46) years who underwent a full IVF cycle. As expected, E2 levels increased by 329.6% from E2min to E2max (108 [47-346] to 464 [241-2471] pg/mL, < 0.05). During the same time, serum PCSK9 levels decreased by 30.8% (245 ± 80 to 170 ± 64 ng/mL, < 0.05). TC, LDL-C, and TGs decreased by 0.4%, 3.8%, and 2.2%, respectively, while HDL-C levels increased by 5.3% (all = NS). The rise in endogenous E2 during an IVF cycle was related with a significant decline in serum PCSK9 levels, but no significant change in plasma lipids during a 7-day period.