Luteinizing hormone: its role, mechanism of action, and detrimental effects when hypersecreted during the follicular phase.

OBJECTIVE: To review studies that have examined the role of LH, its mechanism of action, and its detrimental effects when hypersecreted during the follicular phase.
DESIGN: Important published studies related to this topic were identified through a computerized bibliographic search. PATIENTS, PARTICIPANTS: Review of the need for LH during the follicular phase is based on animal models and women with hypogonadotropic hypogonadism. The association of hypersecretion of LH during the follicular phase with low rates of fertilization and high rates of pregnancy loss is based on clinical studies conducted in patients treated by IVF and ET and by induction of ovulation. The possible mechanism by which the effects occur is based on in vitro studies.
RESULTS: The results of the studies cited in this review are consistent with the two-cell two-gonadotropin hypothesis implying that synergistic action of both FSH and LH is required for appropriate steroidogenesis. It also seems that, whatever the underlying mechanism, a raised serum LH concentration during the follicular phase confers a substantial risk of infertility and early pregnancy loss.
CONCLUSION: By reviewing the literature it appears that LH exhibits an important role in the development of the growing follicle and maturation of the oocyte. It also seems that hypersecretion of LH during the follicular phase implies adverse effects on the fertility process. To further test this hypothesis, we now need systemic assessment of the methods of therapy used for treating patients with polycystic ovary syndrome, in relation to LH secretion and outcome of pregnancy.