Recombinant luteinizing hormone in assisted reproductive technology

The separate but complementary roles of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in stimulating folliculogenesis and ovulation are well established. However, it is not known if there are levels under which low LH concentrations may be equally or suboptimal for oocyte quality and subsequent embryonic development competence. On the other hand, there are some conflicting data related to the high levels of LH promoting follicular atresia and early miscarriage. This has lead to the concept of a 'therapeutic window' of LH for successful conception in assisted reproductive technology (ART) and ovulation induction. In hypogonadotrophic hypogonadism (HH), rLH is effective for supporting FSH-induced follicular development, in a dose related manner and rLH promotes estradiol secretion, enhances the effect of FSH on follicular growth, and permits successful luteinization. Some patients with prolonged and profound down-regulation response like hypogonadotrophic hypogonadal patients and may benefit from concomitant exogenous administration of LH. Retrospective meta-analyses comparing LH-containing regimens with LH-free stimulations have provided conflicting results in normal ovulatory patients. Until recently, human menopausal gonadotrophin (HMG) preparations were the only source of exogenous LH, however, recombinant human luteinizing hormone (rLH) is now available for clinical use, providing a new treatment option. rLH is well characterized and production is tightly controlled resulting in a highly consistent product. In addition, it has been shown that rLH is as effective but safer than human chorionic gonadotrophin (hCG) in inducing final follicular maturation and ovulation.