Chapter 71
The Use of Gonadotropin-Releasing Hormone to Induce Ovulation
Michael D. Scheiber and James H. Liu
Main Menu   Table Of Contents

Search

Michael D. Scheiber, MD, MPH
Clinical Instructor, Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, Cincinnati, Ohio (Vol 15, Chap 71)

James H. Liu, MD
Professor and Director, Division of Reproductive Endocrinology and Infertility, University of Cincinnati, Department of Obstetrics and Gynecology, Cincinnati, Ohio (Vol 5, Chaps 10, 71)

INTRODUCTION
PHYSIOLOGY
INDICATIONS AND PATIENT SELECTION
CLINICAL USE AND PROTOCOLS
EXPECTED OUTCOMES
COMPLICATIONS
COST
FUTURE CONSIDERATIONS
SUMMARY
REFERENCES

INTRODUCTION

Gonadotropin-releasing hormone (GnRH) was first isolated, characterized, and synthesized by Schally and Guillemin in 1971.1,2,3 However, it was the classic work by Knobil and co-workers demonstrating (1) that the pulsatile secretion of GnRH by the hypothalamus is the primary process controlling the menstrual cycle,4 and (2) that tonic GnRH stimulation causes downregulation of the pituitary GnRH receptor, that led to the widespread investigation of the therapeutic potentials of GnRH. Since that time, long-acting synthetic analogues of endogenous GnRH have gained widespread use in clinical gynecology for the treatment of pelvic pathology such as leiomyomas and endometriosis and as adjunctive therapy for use in ovulation induction with gonadotropins.

Since 1980, pulsatile GnRH has also been used with considerable success to stimulate the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland for clinical ovulation induction.5,6 This chapter reviews the physiology and rationale of ovulation induction with pulsatile GnRH, as well as patient selection and indications, therapy protocols, potential pitfalls, and expected outcomes.

Back to Top
PHYSIOLOGY

GnRH is a decapeptide that has been found in a number of mammals, including humans (Fig. 1). In postpubertal primates, GnRH is synthesized in the arcuate nucleus of the hypothalamus and is released in a pulsatile fashion and transported via the portal circulation to the anterior pituitary, where it stimulates the release of FSH and LH from gonadotropes. Immunohistochemical studies suggest that GnRH cells have an origin in the olfactory pit7 and migrate during early development to their final destination in the hypothalamus by approximately 11 weeks' gestation.8 The GnRH gene sequences were first isolated in 1984,9 and the human gene was localized to the short arm of chromosome 8 (Fig. 2).10 The GnRH decapeptide results from the post-translational processing of a larger 92 amino acid polypeptide and is frequently released in tandem with the GnRH-associated peptide (GAP). GAP may play a role in prolactin regulation. GnRH is rapidly degraded in the peripheral circulation, with a half-life of 2 to 8 minutes.11

Fig. 1. The amino acid sequence of the decapeptide gonadotropin-releasing hormone (GnRH), first isolated, characterized, and synthesized in 1971.

Fig. 2. Human GnRH gene consisting of four exons located on the short arm of chromosome 8. Exon I encodes a 5´ untranslated region. Exon II encodes GnRH and includes part of GAP. Exon III encodes GAP. Exon IV encodes the remainder of GAP and an untranslated region.(Zacur HA, Smith YR: Gonadotropin-releasing hormone and analogues in ovulation induction. In Wallach EE, Zacur HA [eds]: Reproductive Medicine and Surgery, pp 639–648. St. Louis, Mosby-Year Book, Inc., 1995; as modified from Sherwood NM, Lovejoy DA, Coe IR: Endocr Rev 14:241, 1993)

A major advance in our understanding of GnRH physiology came in 1978, when Knobil and co-workers4 demonstrated that monkeys with lesions localized to the arcuate region had no detectable endogenous GnRH or gonadotropin release. Continuous replacement of exogenous GnRH in these monkeys led to gonadotropic desensitization resulting from a loss of GnRH receptors on the surface of the gonadotropes. However, exogenous replacement of GnRH in a pulsatile pattern, without varying the frequency or amplitude of administration, resulted in reinitiation of normal menstrual cycles characterized by orderly follicular development and a spontaneous midcycle LH surge. The findings that pulsatile administration of fixed doses of exogenous GnRH in the follicular phase of the primate menstrual cycle could lead to ovulation (and that overstimulation causes pituitary downregulation and unresponsiveness) form the basis for the clinical applications of GnRH use today.

Several features unique to the GnRH system make its pulsatile administration for ovulation induction theoretically advantageous compared to stimulation with either clomiphene citrate or exogenous gonadotropins. First, the GnRH receptors on pituitary gonadotropes increase in response to episodic GnRH stimulation. This “self-priming” function allows an enhanced LH and FSH response to a steady dose of GnRH.17 Second, the feedback communication between the ovary and the pituitary remains intact, thereby allowing physiologic modulation of the cycle response and decreasing the risk of ovarian hyperstimulation or multiple pregnancy. Finally, for patients in whom fertility is a concern, GnRH has no antiestrogenic effects on the endometrium, thus providing a more receptive environment for implantation.

Back to Top
INDICATIONS AND PATIENT SELECTION

Given the aforementioned physiologic considerations, it follows reasonably that the women most likely to benefit from ovulation induction with pulsatile GnRH are those with an ovulatory defect resulting from deficient GnRH secretion. Thus, patients with hypogonadotropic hypogonadism will have the highest response rates. This group includes women with primary GnRH deficiency (e.g., Kallmann's syndrome) as well as those with an intact hypothalamus but decreased GnRH release (e.g., hypothalamic amenorrhea). The success of GnRH stimulation in these patients led the Food and Drug Administration (FDA) to approve the use of intravenous (IV) pulsatile GnRH for ovulation induction in women with primary hypothalamic amenorrhea.

Ovaluation induction with pulsatile GnRH has also been used in many other settings. It has been used as a therapeutic modality in women with disordered endogenous GnRH secretion, such as polycystic ovary syndrome (PCOS), hyperandrogenic anovulation, and late-onset congenital adrenal hyperplasia, who are resistant to ovulation induction with clomiphene citrate. As will be discussed below, however, ovulation and pregnancy success rates in these groups are much lower than in women with hypogonadotrophic hypogonadism. Women with anovulation secondary to hyperprolactinemia respond similarly to those with GnRH deficiency, but the relative ease of administration and efficacy of the specific dopamine agonists make hyperprolactinemia a relatively rare indication for pulsatile GnRH. More logically, GnRH has also been used with success for ovulation induction in unusual causes of hypogonadotropic hypogonadism, such as the sequelae of treatment for cranial tumors18,19 or amenorrheic lactating postpartum women.20

Depending on an infertile couple's history, documentation of tubal patency, normal uterine anatomy, and normal sperm parameters may be indicated before embarking on a course of pulsatile GnRH therapy. For women with anovulation resulting from conditions other than hypogonadotropic hypogonadism, a trial of clomiphene citrate is usually warranted before attempted ovulation induction with GnRH.

Back to Top
CLINICAL USE AND PROTOCOLS

Protocols using pulsatile GnRH and resulting in successful ovulatory responses and clinical pregnancies have been reported with varied doses, frequencies, and routes of administration; these will each be discussed later in more detail. All the clinical methods share in common the delivery of the pulsatile GnRH via a small, portable, programmable infusion pump. Several pumps are available in the United States, and all store a reservoir of GnRH solution and deliver a fixed or variable volume at specified intervals (e.g., Zyklomat, Ferring Laboratories, Ridgewood, NJ; Auto Syringe, Auto Syringe, Hookset, NH; Lutrepulse, Ortho Pharmaceutical, Raritan, NJ). These pumps are similar to those used for insulin or tocolytic therapy, and most deliver the pulse over a 1-minute period.

Route of Administration

Multiple routes of GnRH administration are available. Absorption occurs after IV, subcutaneous (SC), intramuscular (IM), nasal, and sublingual administration.22,23,24 Considerable debate exists over the preferred route of pulsatile GnRH administration for ovulation induction. Several centers have reported successful pregnancies using the SC administration of pulsatile GnRH.5,25,26,27,28 Most centers, however, have reported superior ovulation and pregnancy rates, as well as lower spontaneous abortion rates with IV administration.29,30,31,32,33,34

The pharmacokinetic data clearly suggest the superiority of the IV route.29,35 IV administration of pulsatile GnRH results in a well-defined episodic release of LH and FSH, whereas SC administration of identical GnRH pulses can result in prolonged absorption with a slower sustained rise in LH and FSH without a normal pulsatile pattern and a slower return to baseline (Fig. 3). Advocates of SC administration stress the relative convenience and safety of this route and save IV administration only for those subjects who fail SC therapy. Subsequent to the higher ovulatory rates, however, the FDA has approved only the IV route for pulsatile GnRH administration.

Fig. 3. LH and FSH levels in the same woman after 5-μg pulses of GnRH every 90 minutes administered either intravenously or subcutaneously.(LRF, LH-releasing factor) (Liu JH, Yen SSC: The use of gonadotropin-releasing hormone for the induction of ovulation. Clin Obstet Gynecol 27:975, 1984; as modified from Reid RL, Leopold GR, Yen SSC: Induction of ovulation and pregnancy with pulsatile luteinizing hormone-releasing factor: Dosage and mode of delivery. Fertil Steril 36:553, 1981)

At our institution, we favor the IV route of administration. Using sterile technique, a 22-gauge, 1 1/4-inch Teflon catheter is inserted into a vein in the nondominant forearm. Microbore plastic extension tubing (with a dead space less than 1 mL) is used to connect the catheter to the pump reservoir. Setups will vary depending on the pump and reservoir system chosen. A three-way stopcock between the reservoir and the extension tubing is often useful for refilling the reservoir or removing air from the line in certain setups. In our experience, patients tolerate the IV setup very well, and initial lines are often left in place for an entire cycle. A few programs leave the same peripheral IV in for several cycles,33 whereas others recommend changing the IV site every 3 to 7 days.36 Infection rates are generally low (see Complications section), and patient acceptance has been quite high in our experience.

Pulse Frequency

The pulse frequency of endogenous GnRH in normal women during regular ovulatory menstrual cycles ranges from approximately 95 minutes in the early follicular phase to approximately 60 to 70 minutes in the periovulatory period.37,38,39 Luteal-phase pulses are of decreasing frequency but higher amplitude.

Based on Knobil's work in the monkey, original pulsatile GnRH ovulation induction in humans was largely performed with a fixed pulse frequency.5,30 Excellent rates of ovulation (90% to 100%) and pregnancy have been reported with the use of fixed follicular-phase pulse frequencies of every 90 minutes32 and every 60 minutes,40 with little difference in steroid response, ovulation rates, or pregnancy rates being demonstrated between these two regimens.41 When pulse frequency was extended to 120 minutes, ovulation rates fell to approximately 70%.42 A 60-minute follicular-phase frequency has been shown more effective than a 120-minute frequency at inducing a spontaneous LH surge and ovulation in women with hypothalamic amenorrhea.43

In an effort to mimic the physiologic pulsations of GnRH in the normal menstrual cycle, some centers use a varying pulse frequency. A regimen using a 90-minute pulse frequency in the first week of folliculogenesis, followed by an increase in frequency to every 60 minutes in the midfollicular phase of the induced cycle, followed by a return to slower pulse frequency in the luteal phase, has been well described.33 In sum, the literature to date supports a follicular-phase pulse frequency of 90 minutes or less to achieve maximum spontaneous ovulation rates, and further studies need to be performed to determine whether there is an added benefit to cycle-specific, nonfixed frequency regimens.

Pulse Dosage

Ovulation can be effectively induced over a range of GnRH doses. The optimal dose depends somewhat on the route of administration, because the SC route requires higher doses than the IV route. Studies have shown that a 1-μg pulse of IV GnRH will result in peak concentrations of GnRH within 4 minutes with levels between 200 and 260 pg/mL.44 These values correspond to the lower range of normal reported for pituitary portal blood concentrations (40 to 2000 pg/mL) in humans.45

Martin and associates33 elegantly defined the hormonal effects of varying IV pulse dosage at optimal pulse intervals. At a dosage of 25 ng/kg (1.25 μg/pulse for a 50-kg patient), the mean peak estradiol level was lower than in normal spontaneous cycles, corpus luteum function (as defined by integrated progesterone levels) was lower than normal, and ovulatory rates were only 80%. At 75 ng/kg (3.75 μg/pulse for a 50-kg patient), midcycle estradiol and progesterone levels were indistinguishable from normal cycles, and the ovulatory rate was 95%. At 100 ng/kg (5 μg/pulse for a 50-kg patient), high ovulatory rates were maintained (93%), but peak estradiol and integrated progesterone levels were exaggerated compared to normal cycles (Fig. 4).

Fig. 4. Serum levels of estradiol (E2) and progesterone (P) (mean ± SEM) in women receiving varying doses of IV pulsatile GnRH. Day 0 represents the midcycle surge, and mean ± SEM values in 62 normal ovulatory cycles are represented by the shaded areas. The data represent 10 cycles at 25 ng/kg, 31 cycles at 75 ng/kg, and 25 cycles at 100 ng/kg. (Martin K, Santoro N, Hall J et al: Clinical Review 15: Management of ovulatory disorders with pulsatile gonadotropin-releasing hormone. J Clin Endocrinol Metab 71:1081A, 1990)

Thus, we recommend a starting dose for IV therapy of 75 ng/kg/pulse (approximately 3.5 to 5.0 μg/pulse). For women who do not respond to this pulse dose, the dose can be incrementally increased up to 10 to 20 μg/pulse. We administer our pulses in a 0.9% sodium chloride solution containing 10 μg/mL GnRH and 30 units of heparin/mL. When tailoring optimal dosage regimens, allowances should be made for considerable individual differences in GnRH requirements. Obese patients and those with PCOS may require much higher doses than average.

Clinical Monitoring and Luteal-Phase Support

The clinical monitoring of induced cycles varies with the setting in which therapy takes place, available clinical resources, and the comfort level of the practitioner and patient. Many centers combine serum estradiol and transvaginal ultrasound monitoring with urine ovulation prediction kits for timing of intercourse. A presumptive diagnosis of ovulation is made by clinical or ultrasonographic findings (e.g., disappearance of a dominant follicle with free pelvic fluid on ultrasound, LH surge determined by urine monitoring, elevated progesterone, clear rise in basal body temperature). Others take a more simple approach and use only cycle length and basal body temperature charting as an index of ovulation.

Most patients ovulate within 10 to 20 days of initiation of IV pulsatile GnRH therapy. Cycle variance results largely from the length of the early follicular phase. Women with absolute GnRH deficiencies tend to have longer follicular phases, because the pituitary must be primed for several days before active secretion of FSH and LH.

At our center, for the first treatment cycle, we prefer a combination of ultrasound and urine LH monitoring. During subsequent cycles, usually only LH monitoring is necessary. Serial ultrasound examinations are performed starting about day 10, and urine LH testing is initiated when the mean ultrasound diameter of the lead follicle is 15 mm. Sexual intercourse, or intrauterine insemination in couples with male-factor infertility, is timed by the urinary LH surge. In our experience, the lack of a spontaneous LH surge is rare. This is an important advantage of GnRH-stimulated cycles because it is the administration of human chorionic gonadotropin (hCG) that may play a critical role in the development of ovarian hyperstimulation syndrome in patients undergoing stimulation with gonadotropins. However, in patients with a lead follicle of 23 mm or greater and no spontaneous surge, ovulation may be induced by the IM injection of 5000 units of hCG.

Luteal-phase support of the corpus luteum is essential to the outcome of a GnRH-induced cycle. Three methods are frequently used in clinical practice, but no prospective data exist to suggest the superiority of one method over the other. If the cycle stimulation resulted in the ovulation of a healthy follicle, successful cycle support can be achieved by continuing pulsatile GnRH administration at the same dose and frequency used in the first part of the cycle.46 Other groups have reported achieving successful clinical pregnancies by slowing the pulse frequency to every 4 hours in the luteal phase, with no apparent shortening of the cycle.47 Similar clinical results can be achieved by discontinuing the GnRH pump after ovulation and administering 1500 to 2000 U of exogenous hCG every 3 days for four doses starting 2 days after presumed ovulation. This method is more convenient than continuation of the pump, but it does not allow for multiple monthly cycles using the same catheter, an option that some centers offer.

Pulsatile Gonadotropin-Releasing Hormone and Polycystic Ovary Syndrome

Patients with PCOS or other variants of hyperandrogenic oligo-ovulation present a special challenge for ovulation induction with GnRH. The disordered release of endogenous GnRH and LH in this subpopulation is often exaggerated by pulsatile GnRH therapy. Ovulatory rates in women with PCOS treated with pulsatile GnRH alone are as low as 40% to 60% per cycle.48 However, the addition of GnRH agonist (GnRHa) therapy to downregulate the pituitary and reduce ambient testosterone levels before initiating pulsatile GnRH therapy dramatically improves the outcome in these patients. Filicori and colleagues,49 in a small study, initially showed an increase in ovulatory cycles from 38% to 90% in PCOS patients pretreated with GnRHa. Subsequently, they published the results of 228 GnRH-induced cycles in women with multifollicular ovary, PCOS, and other forms of hyperandrogenic anovulation.40 Seventy-four percent of post-GnRHa cycles were ovulatory compared to 59% of 104 cycles in the same groups of patients without GnRHa pretreatment. In PCOS patients alone, pretreatment with GnRHa improved ovulatory rates from 49% to 71%.

In a small study, pretreatment with GnRHa was shown to be superior to pretreatment with an estrogen-gestagen compound in terms of resultant ovulatory GnRH-induced cycles.50 Pretreatment with GnRHa also reduces the risk of multiple pregnancy in patients with PCOS undergoing ovulation induction with pulsatile GnRH.34

Despite GnRHa pretreatment, luteal-phase steroid secretion remains abnormal after GnRH-induced ovulation in women with PCOS, and elevated spontaneous abortion rates have been reported in those cycles resulting in pregnancy.34 Continuous pulsatile GnRH therapy in women with PCOS has been suggested to improve the endocrine milieu. In women with PCOS treated with 100 ng/kg of IV pulsatile GnRH during consecutive cycles, first cycles were characterized by elevated levels of LH and luteal-phase estradiol compared to second cycles, which better approximated levels found in normal, eumenorrheic women.51 In another study, however, a suboptimal endocrine pattern and a lower ovulatory rate were found when a second post-GnRHa cycle occurred without an initial repeat of analog suppression.49Table 1 summarizes selected series studying ovulation induction with GnRH in women with PCOS.25,32,49,52,53,54,55,56,57,58

TABLE 1. Outcomes with Pulsatile GnRH Therapy in Women with PCOS in Selected Studies


 

No. of

GnRH

Frequency

 

Ovulatory

Pregnancy

Study

Cycles

Dose (μg)

(min)

Route

Cycles (%)

Rate (%)

Saffan25

5

20

120

SC

40

0

Eshel58

108

15

90

SC

48

21

Hurwitz52

12

20–40

120–400

SC

17

0

Coelingh-Bennick53

42

10–20

90

IV

69

28

Ory546

1

90

IV

83

0

 

Burger55

85

5–40

60–120

IV

87

6

Wilson56

9

5–40

90

IV

0

0

Surrey57

9

5

90

IV

22

0

 Post-GnRHa

7

 

 

 

28

0

Filicori49

24

5

60

IV

38

8

 Post-GnRHa

21

 

 

 

90

38

Jansen32

14

2.5–5

60–120

IV

50

7


GnRH = gonadotropin-releasing hormone ; GnRHa = GnRH agonist : PCOS = polycystic ovary syndrome; SC = subcutaneous ; IV = intravenous.
(Modified from Santoro N, Elzahr D : Pulsatile gonadotropin-releasing hormone therapy for ovulatory disorders. Clin Obstet Gynecol 27:975,1984)

In sum, women with PCOS constitute a more challenging population than those with hypothalamic amenorrhea for induction of ovulation with GnRH. For clomiphene-resistant women, however, pulsatile GnRH still represents a safe and relatively effective option that the clinician should consider before pursuing gonadotropin therapy. Pretreatment with GnRHa maximizes cycle potential in women with PCOS.

Back to Top
EXPECTED OUTCOMES

For women with hypogonadotropic hypogonadism, ovulation can be expected to occur in more than 90% of cycles (Table 2). Rates as low as 80% are reported from the earliest studies, but many of these stimulated cycles were performed with SC therapy and suboptimal pulse frequencies. In fact, ovulatory rates are so high in women with hypogonadotropic hypogonadism, that a failure in the delivery system should be considered in those women who do not ovulate. As discussed earlier, ovulatory rates are much lower in women with PCOS. In a review of 600 GnRH-induced cycles, decreased success was noted in overweight patients as well as those with elevated baseline LH, testosterone, and insulin levels.40

TABLE 2. Outcome with Pulsatile GnRH Therapy for Ovulation Induction in Selected Studies


 

Pregnancy

 

Rate per

 

 

No. of

No. of

GnRH

Frequency

 

Ovulatory

Ovulatory

Study

Indications

Patients

Cycles

Dose (μg)

(min)

Route

Cycles (%)

Cycle (%)

Filicori40

HH, HA,

292

600

1.25–20

60–120

IV

75

23

 

 PCOS, others

 

 

 

 

 

 

 

Liu47

HH, HA

17

45

1–10

60–240

IV

82

30

 

 PCOS, others

 

 

 

 

 

 

 

Martin63

HA

41

118

3–15

60–240

IV

93

31

Filicori34

HH, HA, PCOS

114

187

2.5–5

60

IV

76

32

Santoro41

HA

7

20

5

60–240

IV

100

30

Jansen32

HH, HA

26

79

2.5

60

IV

97

34

Braat59

HH, HA

49

272

2–100

60–120

IV

90

23

Skarin28

HA

24

67

1–40

60

SC

96

28


HH = hypogonadotropic hypogonadism; HA = hypothalamic amenorrhea ;PCOS = polycystic ovary syndrome: SC = subcutaneously; IV = intravenously

Pregnancy rates per GnRH-induced cycle for hypogonadotropic patients range from 18% to 32%, with slightly higher rates per ovulatory cycle (see Table 2). Life-table analysis has been performed in a number of studies. Martin and colleagues33 reported the cumulative conception rate using life-table analysis for 21 patients with idiopathic hypogonadotropic hypogonadism and hypothalamic amenorrhea. The cumulative chance of conceiving over 6 GnRH-induced cycles was 94%. Braat and co-workers59 reported a cumulative conception rate of 93% after 12 cycles, with a mean conception rate of 22.5% per cycle. Homburg and colleagues60 reported cumulative pregnancy rates of 93% to 100% at 6 months in women with idiopathic hypogonadotropic hypogonadism, amenorrhea related to low weight, and organic pituitary disease. In women with PCOS, the cumulative pregnancy rates fell to 74% at 6 months. All of these reported pregnancy rates compare favorably to the 73% 6-month cumulative pregnancy rate seen in normal, fertile women.61,62

One retrospective study compared exogenous gonadotropin stimulation (30 patients and 111 cycles) to pulsatile GnRH therapy (41 patients and 118 cycles) for ovulation induction in hypogonadotropic amenorrhea.63 Overall ovulatory rates (93% vs 97%) and pregnancy rates per cycle (29% vs 25%) were not significantly different between the two groups. Life-table analysis, however, revealed a higher cumulative 6-month pregnancy rate for the GnRH group (96%) than the exogenous gonadotropin group (72%). To date, no randomized clinical trial has been performed comparing the two methods of therapy, but the life-table analyses clearly reveal the therapeutic efficacy of pulsatile GnRH therapy in the select group of patients with hypogonadotropic hypogonadism.

Miscarriage rates approximate 25% to 30% in GnRH-induced cycles.40,60,63 These rates tend to be lower in women with hypothalamic amenorrhea and higher in hyperandrogenic women with elevated body mass indexes. The miscarriage rate among women with PCOS who conceive during GnRH-induced cycles approximates 45%.40,58

Back to Top
COMPLICATIONS

The overall incidence of complications with GnRH therapy is low. The risk of multiple gestation with pulsatile GnRH is greater than in the general population, but lower than that seen with exogenous gonadotropin therapy and comparable to that resulting from clomiphene citrate therapy. Rates of multiple gestation resulting from GnRH cycles is in the range of 4% to 8%.33,40,60,63 Martin and co-workers63 reported more than two dominant follicles on ultrasound in 48% of gonadotropin-treated cycles compared to 19% of pulsatile GnRH-induced cycles, whereas three or more dominant follicles were seen in 17% vs 5%, respectively. Homburg and associates60 and Filicori and colleagues40 reported a less than 1% incidence of triplets resulting from GnRH-induced cycles.

Mild ovarian hyperstimulation has occasionally been reported with GnRH-induced cycles,64 but resolves quickly upon discontinuation of the therapy, perhaps because the prolonged stimulus of exogenous hCG is rarely present. Moderate or severe ovarian hyperstimulation, however, is extraordinarily rare. This is in contrast to the reported experience with exogenous gonadotropins plus hCG with 23% of cycles resulting in mild to severe, and occasionally life-threatening, hyperstimulation syndrome.33

Infectious complications are also rare, even with prolonged indwelling IV catheter placement. Superficial phlebitis at IV sites and cellulitis at the site of SC catheters have been reported.65,66 The largest prospective study to date followed 230 catheters for 1958 catheter days.67 Just 11% of all catheter tips cultured positive, and only 2% of 195 blood cultures were positive. All positive blood cultures were obtained from patients with catheters in place for only 4 to 7 days. No positive blood cultures were obtained from patients with 97 catheters in place for more than 7 days. Two of the four positive blood cultures grew Staphylococcus epidermidis and were thought to be possible contaminants. None of the four patients with positive blood cultures were clinically ill, none received antibiotics, and three had follow-up blood cultures within 10 days, all of which were negative.

The data suggest that the use of IV administration is associated with a low incidence of infectious complications. Nevertheless, for women with cardiac valvular disease (e.g., mitral valve prolapse) or any prosthetic device, it may be preferable to use the SC route of administration to minimize the theoretic risk of endocarditis.

The potential of antibody formation with GnRH therapy apparently exists, but has not been extensively studied. A 3% rate of GnRH antibody formation during 3 weeks to 9 months of SC GnRH therapy in 141 men and 22 women has been reported,68 but the clinical significance of these findings remains unclear.

Back to Top
COST

The cost of ovulation induction with GnRH varies from institution to institution and depends largely on the expense of the monitoring performed. Martin and associates33 recently estimated the range of costs for GnRH cycles compared to exogenous gonadotropin cycles. They estimated that a pulsatile GnRH cycle costs $495 to $3180, whereas an exogenous gonadotropin cycle costs between $700 and $5795, depending on the cost of the drug and the type of monitoring used. However, because of the relative risks of hyperstimulation and multiple gestation associated with each method, it is reasonable to assume that most treatment cycles would be in the low range of the GnRH scale (with a minimum of clinical monitoring necessary) and the higher end of the gonadotropin scale (with frequent ultrasound and serum estradiol evaluation necessary).

Back to Top
FUTURE CONSIDERATIONS

The success of pulsatile IV GnRH therapy in inducing ovulation has led to consideration of its utility for in vitro fertilization techniques. Supraphysiologic doses of IV pulsatile GnRH (10 μg/pulse) at 60- to 120-minute intervals has been reported to override successfully the normal estradiol feedback mechanisms and induce multiple follicular development in normal, eumenorrheic women.69 During these stimulated cycles, two to five follicles of mature size on ultrasound were induced in all six subjects. Mean peak estradiol levels were 585 pg/mL. At our center, we have had a successful pregnancy result from in vitro fertilization after oocyte aspiration from a GnRH-stimulated cycle (abstract submitted), and a prospective study using this technique is underway.

Back to Top
SUMMARY

From this overview, it is apparent that pulsatile IV GnRH represents a reliable, acceptable, safe, and effective means of physiologically inducing ovulation in anovulatory women. Patients with hypogonadotropic hypogonadism constitute a small subset of the total infertile population. Yet, for this group of women, pulsatile GnRH therapy essentially restores normal ovulatory and cumulative conception rates with extremely low risks of ovarian hyperstimulation and multiple pregnancy. Women with anovulation resulting from other disorders, such as PCOS, may also benefit from ovulation induction with GnRH. However, ovulation and pregnancy rates are lower than those seen with hypogonadotropic hypogonadism, and a trial of clomiphene citrate should be undertaken before attempting ovulation induction with GnRH. Pretreatment with GnRHa improves the outcome for women with PCOS.

Effective therapy can be administered by either the SC or IV route, although the pharmacologic data as well as our own experience support the superiority of IV administration. With this route, patient acceptance is high and infectious complications are low. The optimal physiologic dose for initial ovulation induction with pulsatile IV GnRH is 75 ng/kg/pulse administered every 60 to 90 minutes. Outpatient clinical monitoring (and, therefore, cycle cost) can be kept to a minimum while patient safety is assured. Spontaneous ovulation is the norm, and luteal-phase support with either continued GnRH or exogenous hCG is mandatory.

It is unclear why ovulation induction with pulsatile GnRH has not enjoyed the widespread use in the United States that it has in Europe as an alternative to exogenous gonadotropin therapy in anovulatory women. It is hoped, however, that its worldwide success will lead to increased usage in the United States and will stimulate further research into its use. Specific projects that need to be performed prospectively include a study to determine whether a variable pulse frequency is superior to a fixed frequency, a randomized clinical trial comparing GnRH therapy to exogenous gonadotropins, and a study examining the benefit of supraphysiologic doses of pulsatile GnRH to be used for multiple follicular development for the assisted reproductive technologies.

Back to Top
REFERENCES

1. Matsuo H, Baba Y, Nair RMG et al: Structure of the porcine LH and FSH releasing factor: I. The proposed amino acid sequence. Biochem Biophys Res Commun 43: 1334, 1971

2. Burgus R, Butcher M, Ling N et al: Structure moleculair du facteur hypothalamique (LRF) d'origine ovine controlant la secretion de l'hormone gonadotrope hypophysaire de luteinisation (LH). CR Acad Sci 273: 1611, 1971

3. Amoss M, Burgus R, Blackwell R et al: Purification, amino acid composition and N-terminus of the hypothalamic luteinizing hormone releasing factor of ovine origin. Biochem Biophys Res Commun 44: 205, 1971

4. Belchetz PE, Plant TM, Nakai Y et al: Hypophysial responses to continuous and intermittent delivery of hypothalamic gonadotropin-releasing hormone. Science 202: 631, 1978

5. Crowley WF Jr, McArthur JW: Stimulation of the normal menstrual cycle in Kallman's syndrome by pulsatile administration of luteinizing hormone-releasing hormone (LHRH). J Clin Endocrinol Metab 51: 173, 1980

6. Leyendecker G, Wildt L, Hansmann M: Pregnancies following chronic intermittent (pulsatile) administration of Gn-RH by the means of a portable pump (“Zyklomat”): A new approach to the treatment of infertility in hypothalamic amenorrhea. J Clin Endocrinol Metab 51: 1214, 1980

7. Schwanzel-Fukuda M, Pfaff DW: Origin of luteinizing hormone-releasing hormone neurons. Nature 338: 161, 1989

8. Bloch B, Gaillard RC, Culler MD, Negro-Vilar A: Immunohistochemical detection of proluteinizing hormone—releasing hormone peptides in neurons in the human hypothalamus. J Clin Endocrinol Metab 74: 135, 1992

9. Seeburg PH, Adelman JP: Characterization of cDNA for precursor of human luteinizing hormone releasing hormone. Nature 311: 666, 1984

10. Yang-Feng TL, Seeburg PH, Francke V: Human luteinizing hormone-releasing hormone gene (LHRH) is located on the short arm of chromosome 8 (region 8p11.2 p21). Somat Cell Mol Genet 12: 95, 1986

11. Jeffcoate SL, Greenwood RH, Holland DT: Blood and urine clearance of luteinizing hormone releasing hormone in man measured by radioimmunoassay. J Endocrinol 60: 305, 1974

12. Yen SSC, Tsai CC, Naftolin F et al: Pulsatile patterns of gonadotropin release in subjects with and without ovarian function. J Clin Endocrinol Metab 34: 671, 1972

13. Santen RJ, Bardin CW: Episodic luteinizing hormone secretion in man. J Clin Invest 52: 2617, 1973

14. Clarke IJ, Cummins JT: The temporal relationship between gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion in ovariectomized ewes. Endocrinology 111: 1737, 1982

15. Levine JE, Ramirez VD: Luteinizing hormone-releasing hormone release during the rat estrous cycle and after ovariectomy, as estimated with push-pull cannulae. Endocrinology 111: 1439, 1982

16. Rasmussen DD, Gambacciani M, Swartz W et al: Pulsatile gonadotropin-releasing hormone release from the human mediobasal hypothalamus in vitro: Opiate receptor-mediated suppression. Neuroendocrinology 49: 150, 1989

17. Clayton RN, Catt KJ: Gonadotropin-releasing hormone receptors: Characterization, physiological regulation, and relationship to reproductive function. Endocr Rev 2: 186, 1981

18. Hall JE, Martin KA, Whitney HA et al: Potential for fertility with replacement of hypothalamic gonadotropin-releasing hormone in long term survivors of cranial tumors. J Clin Endocrinol Metab 79: 1166, 1994

19. Park KH, Park WI, Lee BS et al: Pulsatile gonadotropin-releasing hormone therapy in patients with pituitary tumors treated by surgery and irradiation. Clin Endocrinol 40: 407, 1994

20. Zinaman MJ, Cartledge T, Tomai T et al: Pulsatile GnRH stimulates normal ovarian function in amenorrheic lactating postpartum women. J Clin Endocrinol Metab 80: 2088, 1995

21. Akande EO, Bonnar J, Carr PJ et al: Effect of synthetic gonadotropin-releasing hormone in secondary amenorrhea. Lancet 2: 112, 1972

22. Gonzalez-Barcena D, Kastin AJ, Schlach DS et al: Synthetic LH-releasing hormone (LH-RH) administered to normal men by different routes. J Clin Endocrinol Metab 37: 481, 1973

23. Keller PJ: Treatment of anovulation with synthetic luteinizing hormone-releasing hormone. Am J Obstet Gynecol 116: 698, 1973

24. London DR, Butt WR, Lynch SS et al: Hormonal responses to intranasal luteinizing hormone-releasing hormone. J Clin Endocrinol Metab 37: 829, 1973

25. Saffan D, Seibel MM: Ovulation induction with subcutaneous pulsatile gonadotropin-releasing hormone in various ovulatory disorders. Fertil Steril 45: 475, 1986

26. Seibel MM, Kamrava M, McArdle C, Taymor ML: Ovulation induction and conception using subcutaneous pulsatile gonadotropin-releasing hormone. Obstet Gynecol 61: 292, 1983

27. Hurley DM, Brian RJ, Burger HG: Ovulation induction with subcutaneous pulsatile gonadotropin-releasing hormone: Singleton pregnancies in patients with previous multiple pregnancies after gonadotropin therapy. Fertil Steril 40: 575, 1983

28. Skarin G, Ahlgren M: Pulsatile gonadotropin-releasing hormone (GnRH): Treatment for hypothalamic amenorrhoea causing infertility. Acta Obstet Gynecol Scand 73: 482, 1994

29. Reid RL, Leopold GR, Yen SSC: Induction of ovulation and pregnancy with pulsatile luteinizing hormone-releasing factor: Dosage and mode of delivery. Fertil Steril 36: 553, 1981

30. Leyendecker G, Struve T, Plotz EJ: Induction of ovulation with chronic intermittent (pulsatile) administration of LH-RH in women with hypothalamic and hyperprolactinemic amenorrhea. Arch Gynecol 229: 177, 1980

31. Loucopoulos A, Ferin M, Vande Wiele RL et al: Pulsatile administration of gonadotropin-releasing hormone for induction of ovulation. Am J Obstet Gynecol 148: 895, 1984

32. Jansen RPS, Handelsman DJ, Boyland LM et al: Pulsatile gonadotropin-releasing hormone for ovulation-induction in infertile women: I. Safety and effectiveness with outpatient therapy. Fertil Steril 48: 33, 1987

33. Martin K, Santoro N, Hall J et al: Clinical Review 15: Management of ovulatory disorders with pulsatile gonadotropin-releasing hormone. J Clin Endocrinol Metab 71 (5): 1081A, 1990

34. Filicori M, Flamigni C, Meriggiola MC et al: Endocrine response determines the clinical outcome of pulsatile gonadotropin-releasing hormone ovulation induction in different ovulatory disorders. J Clin Endocrinol Metab 72: 965, 1991

35. Handelsman DJ, Jansen RPS, Boylan LM et al: Pharmacokinetics of gonadotropin-releasing hormone: Comparison of subcutaneous and intravenous routes. J Clin Endocrinol Metab 59: 739, 1984

36. Blacker CM: Ovulation stimulation and induction. Endocrinol Metab Clin North Am 21: 57, 1992

37. Elkind-Hirsch K, Ravnikar V, Tulchinsky D et al: Episodic secretory patterns of immunoreactive luteinizing hormone-releasing hormone (IR-LH-RH) in the systemic circulation of normal women throughout the menstrual cycle. Fertil Steril 41: 56, 1984

38. Veldhuis JD, Beitins IZ, Johnson ML et al: Biologically active luteinizing hormone is secreted in episodic pulsations that vary in relation to stage of the menstrual cycle. J Clin Endocrinol Metab 58: 1050, 1984

39. Filicori M, Santoro N, Merriam GR, Crowley Jr WF: Characterization of the physiological pattern of episodic gonadotrophin secretion throughout the human menstrual cycle. J Clin Endocrinol Metab 62: 1136, 1986

40. Filicori M, Flamigni C, Dellai P et al: Treatment of anovulation with pulsatile gonadotropin-releasing hormone: Prognostic factors and clinical results in 600 cycles. J Clin Endocrinol Metab 79: 1215, 1994

41. Santoro N, Wierman ME, Filicori M et al: Intravenous administration of pulsatile gonadotropin-releasing hormone in hypothalamic amenorrhea: Effects of dosage. J Clin Endocrinol Metab 62: 109, 1986

42. Braat DDM, Schoemaker J: Endocrinology of gonadotropin-releasing hormone induced cycles in hypothalamic amenorrhea: The role of the pulse dose. Fertil Steril 56: 1054, 1991

43. Filicori M, Flamigni C, Campaniello E et al: Evidence for a specific role of GnRH pulse frequency in the control of the human menstrual cycle. Am J Physiol 257: E930, 1989

44. Miller DS, Reid RR, Cetel NS et al: Pulsatile administration of low-dose gonadotropin-releasing hormone: Ovulation and pregnancy in women with hypothalamic amenorrhea. JAMA 250: 2937, 1983

45. Antunes JL, Carmel PW, Housepian EM, Ferin M: Luteinizing hormone-releasing hormone in human pituitary blood. J Neurosurg 49: 382, 1978

46. Filicori M, Valdiserri A, Flamigni C et al: Ovulation induction with pulsatile gonadotropin-releasing hormone: Technical modalities and clinical perspectives. Fertil Steril 56: 1, 1991

47. Liu JH, Yen SSC: The use of gonadotropin-releasing hormone for the induction of ovulation. Clin Obstet Gynecol 27: 975, 1984

48. Santoro N, Elzahr D: Pulsatile gonadotropin-releasing hormone therapy for ovulatory disorders. Clin Obstet Gynecol 36: 727, 1993

49. Filicori M, Flamigni C, Camaniello et al: The abnormal response of polycystic ovarian disease patients to exogenous pulsatile gonadotropin-releasing hormone: Characterization and management. J Clin Endocrinol Metab 69: 825, 1989

50. Gerhard I, Matthes J, Runnebaum B: The induction of ovulation with pulsatile gonadotropin-releasing hormone (GnRH) administration in hyperandrogenic women after down-regulation with buserelin or suppression with an oral contraceptive. Hum Reprod 8: 2033, 1993

51. Corenthal L, Von Hagen S, Larkins D et al: Benefits of continuous physiological pulsatile gonadotropin-releasing hormone therapy in women with polycystic ovarian syndrome. Fertil Steril 61: 1027, 1994

52. Hurwitz A, Rosenn B, Palti Z et al: The hormonal response of patients with polycystic ovarian disease to subcutaneous low-frequency pulsatile administration of luteinizing hormone-releasing hormone. Fertil Steril 46: 378, 1986

53. Coelingh-Bennick HJT, Weber HW, Alsbach HPJ, Thijssen JHH: Induction of ovulation by pulsatile intravenous administration of GnRH in polycystic ovarian disease. Fertil Steril 41: 34S, 1984

54. Ory SJ, London SN, Tyrey L, Hammond CB: Ovulation induction with pulsatile gonadotropin-releasing hormone administration in patients with polycystic ovarian syndrome. Fertil Steril 43: 20, 1985

55. Burger CW, Korsen TJ, Hompes PG et al: Ovulation induction with pulsatile luteinizing hormone-releasing hormone in women with clomiphene citrate-resistant polycystic ovary-like disease: Clinical results. Fertil Steril 46: 1045, 1986

56. Wison JM, Traub AI, Sheridan B et al: Conventional dose intravenous pulsatile GnRH therapy does not induce ovulation in polycystic ovarian disease. Acta Endocrinol (Copenh) 117: 289, 1988

57. Surrey ES, de Ziegler D, Lu JKH et al: Effects of gonadotropin-releasing hormone (GnRH) agonist on pituitary and ovarian responses to pulsatile GnRH therapy in polycystic ovarian disease. Fertil Steril 52: 547, 1989

58. Eshel A, Abdulwahid NA, Armar NA: Pulsatile luteinizing hormone-releasing hormone therapy in women with polycystic ovary syndrome. Fertil Steril 49: 956, 1988

59. Braat DD, Schoemaker R, Schoemaker J: Life table analysis of fecundity in intravenously gonadotropin-releasing hormone-treated patients with normogonadotropic and hypogonadotropic amenorrhea. Fertil Steril 55: 266, 1991

60. Homburg R, Eshel A, Armar NA et al: One hundred pregnancies after treatment with pulsatile luteinising hormone releasing hormone to induce ovulation. Br Med J 298: 809, 1989

61. Guttmacher AF: Factors affecting normal expectancy of conception. JAMA 161: 855, 1956

62. Tietze C: Fertility after discontinuation of intrauterine and oral contraception. Int J Fertil 13: 385, 1968

63. Martin KA, Hall JE, Adams JM, Crowley WF: Comparison of exogenous gonadotropins and pulsatile gonadotropin-releasing hormone for induction of ovulation in hypogonadotropic amenorrhea. J Clin Endocrinol Metab 77: 125, 1993

64. Skarin G, Millius SJ, Wide L: Pulsatile low dose luteinizing hormone-releasing hormone treatment for ovulation induction of follicular maturation and ovulation in women with amenorrhea. Acta Endocrinol (Copenh) 101: 78, 1982

65. Hurley DM, Brian R, Outch K et al: Induction of ovulation and fertility in amenorrheic women by pulsatile low dose gonadotropin-releasing hormone. N Engl J Med 310: 1069, 1984

66. Molloy BG, Hancock KW, Glass MR: Ovulation induction in clomiphene nonresponsive patients: The place of pulsatile gonadotropin-releasing hormone in clinical practice. Fertil Steril 43: 26, 1985

67. Hopkins CC, Hall JE, Santoro NF et al: Closed intravenous administration of gonadotropin-releasing hormone (GnRH): Safety of extended peripheral intravenous catheterization. Obstet Gynecol 74: 267, 1989

68. Meakin JL, Keogh EJ, Martin CE: Human anti-luteinizing hormone-releasing hormone antibodies in patients treated with synthetic luteinizing hormone-releasing hormone. Fertil Steril 43: 811, 1985

69. Liu JH, Durfee R, Muse K, Yen SSC: Induction of multiple ovulation by pulsatile administration of gonadotropin-releasing hormone. Fertil Steril 40: 18, 1983

Back to Top