Sensitive LH and FSH assays for monitoring low serum levels in men undergoing steroidal contraception

Background and objectives Current immunoassays for detecting serum FSH and LH are not sufficiently sensitive to detect the markedly reduced levels in men undergoing steroidal hormonal treatment for contraceptive purposes. The purpose of this study was to increase the sensitivity of available LH and FSH immunofluorometric (Delfia(R)) assays in order to allow a better unders tanding of the importance of gonadotrophin suppression in achieving the opt imal suppression of sperm count. Design and patients Assay conditions were modified by increasing serum samp le volume, the inclusion of either FSH- or LH-depleted serum to reduce the resulting matrix effects and extending incubation times. The microassays we re applied to serum from 10 men administered testosterone enanthate with or without depot medroxyprogesterone acetate for 12 weeks as part of a contra ceptive trial. Results The assay sensitivities were increased to 0.005 IU/I for LH and 0.0 10 IU/I for FSH, representing a five- to six-fold increase In sensitivity c ompared with existing assays. In the clinical trial, serum LH levels were s uppressed to near or below the level of assay detection (mean 0.014 IU/I < 0.4% of pretreatment values) while in eight of 10 men, plasma FSH levels we re detectable (0.04-0.07 IU/I, 1-5% of pretreatment values). These FSH leve ls would not have been detected by current assays. Conclusions The increased sensitivities of the LH and FSH assays enabled th e detection of gonadotrophins that were <0.4% of pretreatment serum levels. Using these methods, serum LH was suppressed to nondetectable or near nond etectable levels while serum FSH was highly suppressed but still detectable in the majority of men undergoing steroidal treatment for contraceptive pu rposes.