The effects of levonorgestrel, desogestrel and gestodene on the pulsatile release of luteinizing hormone in oral contraceptive users.

The dynamics of luteinizing hormone (LH) and follicle stimulating hormone (FSH) release were investigated in 60 long-term oral contraceptive (OC) users. Five different types of OC, all containing the same amount of estrogens were studied: three monophasic preparations containing levonorgestrel, desogestrel and gestodene, respectively, and two triphasic formulations, containing levonorgestrel or gestodene. Thirteen healthy, normally cycling volunteers served as controls. Blood sampling was performed at 10-min intervals during a 6-h period to determine the pulsatile release of LH. LH and FSH were measured using a sensitive immunoradiometric assay. Pulse patterns were classified on the basis of the overall LH level, as well as on the character of the LH pulses, according to both frequency and amplitude characteristics. Pulsatile LH release was maintained during OC use. After the 7-day pill-free interval, FSH levels as well as the LH pulse patterns were comparable to those of early follicular-phase controls. FSH levels and FSH release in response to a gonadotropin releasing hormone (GnRH) challenge were profoundly suppressed in all OC users, as early as day 8 of the pill cycle. LH release during the pill cycle was characterized by either a low frequency (median 1 pulse/6 h), high amplitude (median 2.5 IU/l) pulse pattern or by a pattern of low-amplitude pulses (median 0.2 IU/l) and low basal LH levels (median 0.2 IU/l). The distribution of these pulse patterns showed marked differences between different OC preparations and depended on both the type and dose regimen of the gestagenic component of the OC.