LH et déclenchement de l'ovulation

Actions of the LH peak

Mechanisms of the LH-peak triggered ovulation

• basic action of estradiol, with combined facilitating effect of progesterone, in sensitizing the pituitary to the pulse effect of GnRH ;
• LH level thresholds different to obtain resumption of oocyte meiosis and secretion of progesterone (5% of peak) and for follicle rupture (95% of peak).

Interest of reproducing the LH peak in stimulated cycles

• hCG: effective but high risk of overstimulation ;
• GnRH agonists: effective for simple ovulation induction, minimal risk of overstimulation but can reduce luteal phase quality as compared to hCG ;
• recombinant hCG: very improved tolerance ;
• recombinant LH: small risk of hyperstimulation and more physiological levels of estradiol.