Conventional GnRH Antagonist (GnRHa) Protocols:
GnRH antagonists (e.g. Ganirelix, Cetrotide, and Orgalutron) are currently used with many controlled ovarian stimulation (COS) protocols. The conventional approach is to administer 250mcg antagonist, daily starting from the 6th-8th day after commencing ovarian stimulation with gonadotropins. This traditional approach is in my opinion, best suited to younger patients who have normal ovarian reserve (AMH>2.0ng/ml or 15pmol/L) and are “good responders” to COS, provided that the stimulation cycle is launched with a spontaneous menstrual cycle and is not launched coming off a birth control pill (BCP) or following prolonged premenstrual hormonal suppression. However, this approach can in my opinion be decidedly disadvantageous when used in older women (>39y), women with diminished ovarian reserve (DOR) or women with polycystic ovarian syndrome (PCOS) who all tend to have increased LH bioactivity.
Background information: An important role of LH is to promote male androgen hormone (testosterone, androstenedione and DHEA) production by ovarian connective tissue (stroma or theca) that surrounds follicles. While androgens (predominantly testosterone) represent the building blocks from which follicle granulosa cells manufacture estrogen and are thus essential for optimal follicular growth and egg development, too much LH activity can lead to over-production/exposure to ovarian androgens which might compromise follicular/egg development. Accordingly, when it comes to older women and those DOR and PCOS who tend to have excessive LH-induced ovarian testosterone, it is (in my opinion) essential to maintain LH activity at a subliminal level. Thus LH suppression needs to be in place from the very start of COS…not much later as when antagonist suppression is commenced 6-8 days into the COS process. Accordingly, I believe that GnRH antagonist treatment should be commenced from the very initiation of ovarian stimulation…and that is the concept upon which the agonist/antagonist conversion protocol (A/ACP) is based….see below.
Bear in mind that the main reason for using antagonist suppression is to avoid the “Premature LH Surge”. This is a condition where high ovarian LH activity propagates androgen-induced “follicular exhaustion” and egg dysmaturity. The term “premature LH surge” is a misnomer since it does not involve a sudden “surge” or sporadic rise in LH. In actuality it occurs as a steady rise in LH activity (a “staircase effect”) which elicits a progressive increase in ovarian stromal androgens that ultimately exhausts follicle development and compromises egg “competency”. A more accurate term might be “premature luteinization.” Such poorly developed eggs will often respond to the hCG trigger by becoming aneuploid (a numerical chromosomal abnormality
Thus, trying to avoid “premature luteinization” by administering GnRH antagonist 6-8 days into the COS cycle, is like” shutting the gate after the horse has already left the stable”.
The long pituitary down-regulation COS protocol:
Here, administration of a GnRH-agonist (Lupron, Superfact, and Buserelin) several days before COS is initiated, expunges all LH from the pituitary gland, exhausting it of reservoired LH. Thereupon, agonist administration is continued until the hCG “trigger”. In this way, developing follicles and eggs are protected throughout COS, from over-exposure to LH-induced androgens…thereby avoiding “premature luteinization”. In my opinion, this approach is ideally suited to younger women who have normal LH, normal or increased ovarian reserve (e.g. those with PCOS) and those who have DOR. The downside of this approach is that the GnRHa (Lupron/Buserelin) can competitively bind with ovarian follicle stimulating hormone (FSH) receptors and suppress ovarian response to gonadotropins, something that is more likely to occur with older women and those who have DOR. I introduced the Agonist/Antagonist Conversion Protocol (A/ACP) more than 15 years ago to try and counter this effect.
The agonist/antagonist conversion protocol (A/ACP):
With the A/ACP, GnRH antagonist (Ganirelix, Cetrotide, and Orgalutron) is administered by daily injection from the onset of COS. The A/ACP COS-cycle is launched with the woman coming off a monophasic birth control pill that was administered starting in the 1st 5 days of the preceding cycle and continued for at least 10 days. The BCP is then overlapped with an agonist (e.g. Lupron/buserelin) for three days, whereupon the BCP is stopped and the agonist (Lupron/buserelin) is continued until the onset of menstruation. At or around this point, the agonist (Lupron/Buserelin) is supplanted by an antagonist (Cetrotide/Ganirelix/Orgalutron) and concurrently COS is initiated using an FSH-dominant bias (mainly Follistim/Gonal-F/ Puregon + a small dosage of a menotropins such as Menopur). The combined antagonist/gonadotropin therapy is continued until the hCG trigger. For the reasons cited above, I prescribe some form of the A/ACP for my older IVF patients and those with DOR.
A/ACP with estrogen priming: The A/ACP can be modified for women with very severe DOR through incorporation of “estrogen priming”. We have reported on the fact that the administration of intramuscular estradiol starting about a week prior to commencement of COS. This often markedly enhances ovarian response (presumably by “estrogen priming” enhancing the sensitivity of ovarian FSH-receptors).
There is one draw-back to the use of the A/ACP. This is the fact that prolonged administration of GnRH antagonist throughout the stimulation phase of the COS cycle compromises the predictive use of serial plasma estradiol measurements as an indication of ovarian response to COH. The blood estradiol levels tend to be much lower in comparison with cases where GnRHa alone is used. The reason for the lower blood concentration of estradiol seen with prolonged exposure to GnRH-antagonist might be due to the result of subtle, antagonist-induced alterations in the configuration of the estradiol molecule, such that currently available commercial test used to measure estradiol levels are rendered less sensitive/specific. Accordingly, when the A/ACP protocols are employed, we rely much more heavily on the measurement of follicle growth by ultrasound than on the estradiol levels. Because of this downside, I refrain from using this approach in “high responders” who may be at risk of developing of severe ovarian hyperstimulation syndrome (OHSS) and in whom the accurate measurement of plasma estradiol plays a very important role in the safe management of their COS cycles.