Does the addition of luteinizing hormone in ovarian stimulation protocols improve the outcome?

Ovarian stimulation is an integral part of assisted reproductive technologies (ART). Under physiologic conditions, both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activity is necessary to guarantee follicle growth and maturation. This can be shown in patients with hypogonadotrophic hypogonadism, who have no endogenous FSH or LH activity. The use of FSH alone in these patients does not result in sufficient follicle growth and oocyte quality. Approximately 75IU of LH activity per day is necessary to guarantee optimal success. The use of gonadotropin-releasing hormone (GnRH) agonists in normogonadotrophic patients may result in suppression of LH levels below a certain threshold, resulting in suboptimal outcomes. The question under discussion in this article is the threshold level of LH below which exogenous LH activity should be added to provide optimal ovarian response. Different studies indicate that the endogenous LH level should be 0.5-1.5IU in long-term protocol situations. Patients treated in ultra-long GnRH agonist protocols, as well as older patients, patients with a low response to gonadotropin treatment, and patients treated with a GnRH antagonist protocol may benefit from exogenous LH activity. There are three ways of adding LH activity in ovarian stimulation cycles. Nowadays, lutropin alfa (recombinant LH) may be the optimal choice since it has no chorionic gonadotropin activity and allows individual dosage titration. Every menotropin preparation currently on the market contains some chorionic gonadotropin activity. However, more data are necessary before evidence-based recommendations regarding LH supplementation in ovarian stimulation protocols can be given.