Soluble luteinizing hormone receptor in follicular fluid and the association with reproductive function during IVF and ICSI

The need for assisted reproductive technology (ART) has increased worldwide, leaving a negative impact on both physical and emotional health of the individual as well as on society depending on child births, thus biomarkers that can increase the success of ART are warranted. The luteinizing hormone/choriogonadotropin receptor (LHCGR) is released into blood and follicular fluid, and the level of soluble LHCGR (sLHCGR) in serum has previously been suggested to predict chances of pregnancy and live birth rate after ART. We aimed to investigate whether sLHCGR originates from the ovary and if serum or follicular fluid sLHCGR can predict the likelihood of pregnancy or live birth. A total of 133 women referred to a fertility clinic were included in the study, in total 203 trials of ART were performed. sLHCGR was analyzed in 170 follicular fluid samples and 75 serum samples. Interestingly, serum levels of sLHCGR were higher than follicular fluid levels (0.51 vs. 0.31 pmol/mL, p = 0.020) and a positive correlation in the two compartments was identified (r² 0.770, p < 0.0001), suggesting an extragonadal origin of sLHCGR. Follicular levels of sLHCGR were associated with follicular SHBG and free testosterone. Follicular/serum-ratio of sLHCGR was inversely associated with both serum- and follicular AMH. However, no association was found between sLHCGR and antral follicle count, which questions a link with folliculogenesis. Neither serum nor follicular fluid sLHCGR levels could predict pregnancy or live births in this cohort. Further studies are needed to clarify the role of sLHCGR in the ovaries.