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 horm one (FSH) release were investigated in 60 long-term oral contraceptive (OC) users. Five different types of OC, all containing the same amoun t of estrogens were studied: three monophasic preparations containing levonorgestrel, desogestrel and gestodene, respectively, and two triph asic formulations, containing levonorgestrel or gestodene. Thirteen he althy, 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 i mmunoradiometric assay. Pulse patterns were classified on the basis of the overall LH level, as well as on the character of the LH pulses, a ccording to both frequency and amplitude characteristics. Pulsatile LH release was maintained during OC use. After the 7-day pill-free inter val, FSH levels as well as the LH pulse patterns were comparable to th ose of early follicular-phase controls. FSH levels and FSH release in response to a gonadotropin releasing hormone (GnRH) challenge were pro foundly suppressed in all OC users, as early as day 8 of the pill cycl e. 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 puls e patterns showed marked differences between different OC preparations and depended on both the type and dose regimen of the gestagenic comp onent of the OC.