Pulsatile intravenous gonadotrophin releasing hormone for ovulation induction: determinants of follicular and luteal phase responses

Abstract

When anovulation results from a deficiency of gonadotrophin-releasing hormone (GrRH), substitution therapy with pulsatile peripheral i.v. GnRH is almost always successful. A review of published papers leads to the following conclusions for achieving the best results: (i) the i.v. route is superior to the s.c. route; (ii) the pulse interval should lie between 90 and 60 min, and may be shortened, but not lengthened, as follicular response takes place; (iii) the pulse dose for i.v. administration should be approximately 75 ng/kg (in practice, 2.5 micrograms/pulse for women weighing < 50 kg and 5.0 micrograms/pulse for women weighing > 50 kg is satisfactory). The more profound the degree of hypothalamic and pituitary suppression when GnRH is started, the longer the preliminary rise in FSH will last and the longer will be the duration of the follicular phase. The greater the tendency towards exaggerated LH release (indicating polycystic ovary syndrome), the less likely it is that satisfactory follicular development will follow. The luteal phase depends on (i) the adequacy of follicular development, (ii) the adequacy of the ovulatory stimulus, and (iii) continued trophic stimulus from LH or from administered human chorionic gonadotrophin. Ovulation rates with pulsatile GnRH in hypothalamic chronic anovulation should exceed 95% and appear limited only by technical failures.