1. Types and their physicochemical properties
(1) Menopausal gonadotropin (HMG): extracted from the urine of postmenopausal women. 1959 Israelis were the first to apply it in clinical practice to induce ovulation and obtain a full-term delivery. 80s domestic production and application have begun. Each HMG contains 75 IU each of FSH and LH.
(2) purified follicle stimulating hormone (pure FSH): the LH contained in HMG is not good for inducing super ovulation, after purification, it contains 75 IU of FSH and <1 IU of LH per stick. 0.001 IU, and does not contain other proteins, and can be injected subcutaneously.
(3) Chorionic gonadotropin (HCG): its chemical structure and biological activity is similar to LH HCG in the body the first half-life of 5-6h, the second half-life of 23.9h, so an injection of HCG 10000IU can produce the equivalent of the natural cycle before ovulation LH peak 20 times the effectiveness, and the effect is long-lasting, help support the luteal function.
2. Mechanism of action: HMG contains FSH and LH, which can initiate the recruitment, selection, dominance and maturation of follicles and promote the synthesis of sex hormones; while HCG has the biological activity of LH, a single high dose can promote follicular maturation and ovulation, and can support luteal function. After the use of HMG to induce follicular development and maturation, HCG can promote ovulation.
3. Indications: Gn is indicated for those with hypothalamic-pituitary-ovarian axis (HPOA) hypofunction or ineffective CC treatment and is divided into 4 categories.
Category I: hypothalamic-pituitary failure with low Gn and E. Hypothalamic-pituitary failure clinically manifests as primary or secondary amenorrhea with low endogenous Gn (FSH, LH) and E with normal PRL concentration and no occupying lesions in the hypothalamus and pituitary gland. These include Sheehan’s syndrome (Sheehan), hypofunction after pituitary resection or radiation therapy, and Kallman’s syndrome.
Category 2: Hypothalamic-pituitary dysfunction with normal Gn and E and normal PRL. Women in this group are anovulatory due to gonadal axis dysfunction. This manifests clinically as several types of menstrual disorders, including scanty menstruation, amenorrhea, anovulation, or luteal dysfunction. The common PCOS and amenorrhea and overflow syndrome (A-G sign) belong to this category.
The third category: high Gn and low E, mostly seen in premature ovarian failure (POF), ovarian insensitivity syndrome (ROS), etc.
The first category of disease is the best indication for HMG treatment; the second category of patients first try CC and other treatments, and then try HMG when there is no response; the third category is not an indication for HMG treatment, but in young women this condition may be temporary, especially ROS, and there are individual cases of successful trial of HMG treatment both at home and abroad.
Category IV: Preparation for in vitro fertilization-embryo transfer (IVF-ET) or other gamete transfer (GIFT) (intrafallopian tube gamete transfer, intrauterine gamete transfer). With normal blood Gn and normal gonadal axis regulation and feedback, the purpose of using Gn is to raise the Gn level in the peripheral blood during the recruitment phase of the follicle to exceed the threshold required for more follicles in the pre-recruitment phase to enter recruitment, thus achieving multiple follicle recruitment. At the same time, more follicles can overcome the follicular selection mechanism during follicular development and continue to develop into mature follicles, thus achieving the purpose of promoting superovulation to facilitate the recovery of more eggs and improve the success rate of assisted reproduction techniques.
4. Contraindications.
(1) Hyperprolactinemia (HPRL): should be treated with bromocriptine first. HMG should be used only when PRL is reduced to normal and there is still no ovulation and treatment with CC is ineffective.
(2) Hypergonadotropic (HGn) anovulation: If FSH and LH values are ≥ 40 IU/L, it indicates ovarian failure. There are usually two conditions.
① ovarian insensitivity syndrome to Gn (ROS): there are residual oocytes in the ovary, which can be treated with GnRH agonist to suppress HGn followed by HMG-HCG, and there are cases of obtaining pregnancy.
(2) Premature ovarian failure (POF): there is a lack of oocytes in the ovaries and HMG-HCG treatment is not indicated, but it is more difficult to distinguish between the two clinically.
(3) With other infertility factors: such as fallopian tube obstruction, male partner with azoospermia or oligospermia, HMG can only be used if cured.
(4) With tumors: such as uterine fibroids, especially submucosal fibroids; large ovarian tumors with suspected malignant changes.
(5) Pregnant or lactating women.
(6) Uterine bleeding of unknown origin.
(7) Those with sexual organ malformations that are not suitable for pregnancy.
5.Pre-treatment preparation.
The size of the uterus must be known before medication. If the uterus is dysplastic, estrogen-progestin cycle therapy should be used first to promote normal uterine development before medication. Do a tubal imaging to accurately understand the patency, morphology and function of the fallopian tubes; do a general physical examination to understand the health status. Both parties should check ASAb and husband’s semen are normal before using the drug.
6. Threshold dose of HMG.
There is no strict standard for the size of HMG dosage. The minimum effective dose of HMG to stimulate follicle development is called the threshold value, which varies from patient to patient. If the dose is below the threshold, the follicles cannot initiate growth, and this threshold is independent of the course of treatment. If 110-130% of the threshold is given, the follicles will develop normally; above this dose, there is an increased risk of ovarian hyperstimulation syndrome (OHSS) and multiple pregnancies. The responsiveness of follicles to HMG varies from person to person, and even in the same patient the response of follicles to HMG varies from period to period. The dose of HMG should be adjusted according to the patient’s responsiveness to HMG. If the dose is too high, it is not only expensive but also detrimental to egg quality, fertilization and implantation, decreasing the pregnancy rate and increasing the occurrence of OHSS. Clinical use should be informed by the first course of treatment failure to find out what the threshold dose of HMG causing follicular response is
7. Treatment options and methods.
(1) Treatment of hypothalamic-pituitary failure
Such as sheehan syndrome, post-pituitary resection hypofunction, kallman’s sign, etc. Estrogen and progesterone cycle therapy can be applied to develop the uterus before medication, as it is more difficult to conceive in those with a uterine cavity depth ≤ 6 cm.
HMG+HCG: Start on day 5 of menstruation, 75 IU, qd×7d. After one week if cervical mucus score and ultrasound show no response in follicle size, change to 150 IU/d. After one week if there is still no change, increase to 225 IU/d until follicle maturity. If cervical mucus score (CMS) ≥8, follicles ≥18mm and no other follicles >14mm, HMG is stopped and HCG 5000~10000IU is given intramuscularly. If the ovaries still did not respond, it means that the ovaries lacked follicles or the follicles in the ovaries did not respond to HMG and no further treatment was needed.
In a case of primary amenorrhea, it took 104 doses of HMG to produce a response, and it took 135 doses for the follicles to mature and ovulate.
The starting dose of HMG should be adjusted flexibly according to the body mass index (BMI) and previous ovulation promotion.
Intermittent use of HMG: mostly used for mild ovulation disorders. Generally, the total amount of HMG in the 1st course should not exceed 6 to 8 doses. Divide this total amount into 3 equal parts and give HMG on days D3, 5, 7 or D1, 4, 8 respectively, and HCG on days 10~14 to stimulate ovulation.
(iii) HMG + HCG + growth hormone (GH): Growth hormone increases the responsiveness of the ovaries to HMG stimulation, so adding a larger dose of GH in cases of pituitary failure can reduce the HMG dosage and shorten the average number of treatment days. GH 24 IU is usually given at the same time as starting HMG therapy.
(2) Treatment of WHO subtype II cases of PCOS.
PCOS is a typical case of gonadal axis dysfunction and remains a very difficult problem in ovulation promotion therapy to date. Since such patients have endogenous Gn and E, CC and TMX treatment is usually tried first. If there is no response to treatment, HMG or pure FSH treatment can be tried. Since PCOS patients are prone to OHSS or superfetus pregnancy after HMG+HCG treatment, and most of them have severe disease, the treatment should be done with caution. In addition to the commonly used HMG incremental regimen, low-dose incremental and decremental regimens are more applicable.
(1) Low-dose incremental method: The usual starting dose is 37.5~75 IU/d and can be started at any time during menstruation. If the follicle responds, the dose is maintained at the original dose. If the follicle does not respond, HMG 37.5~75 IU is added every 5~7 days until the follicle responds and then the original dose is maintained until the follicle matures. Ovulation mostly occurred 18-36 h after HCG injection, and patients were instructed to have intercourse daily on the day of HCG injection and 2 days thereafter. With 1391 cycles of this regimen, the rate of single follicle development was 69%, the rate of multiple pregnancy was only 5.7%, and the incidence of OHSS was 1.4%.
(ii) Low-dose decreasing method: The selection of the dominant follicle in the normal menstrual cycle is related to the feedback regulation of E. The dominant follicle has a strong ability to secrete E and is more sensitive to FSH than other follicles. Non-dominant follicles require higher levels of FSH for growth and development, and they will occlude when FSH levels drop. The decremental method is based on this theory. The starting dose is usually 150 IU/d and the taper is started when the follicle diameter is ≥10 mm, with a reduction of 37.5 IU/d every 2 days to 75 IU/d and continued until HCG day.
The single follicle development rate of this regimen was 56%, the pregnancy rate per ovulation cycle was 16%, and the cumulative pregnancy rate was 47%.
(iii) Low-dose incremental and decremental sequential method: The CC regimen combines the features of both incremental and decremental methods, starting with the application of a low-dose incremental regimen that halves the FSH until HCG day when the dominant follicle reaches 14 mm in diameter. The low-dose incremental regimen is started to find the FSH threshold for ovarian response, while the reduction of FSH in the late follicular phase allows for atresia of the excess follicles while the dominant follicle continues to grow and facilitates single follicle development. A study showed that the sequential and low-dose incremental regimens were both effective, with the same pregnancy rate and no OHSS in both regimens. in addition, the HCG day and luteal phase E2 levels and the number of 14mm-15mm follicles on HCG day were lower in the sequential regimen than in the low-dose incremental regimen, and the miscarriage rate was lower in the sequential regimen (15%, 40%).
④CC+HMG: CC50-250mg/d on day 2-5 of the menstrual cycle, followed by HMG application and HCG to induce ovulation when the follicles are mature. the CC method can reduce the HMG dosage.
⑤ HMG+DXM: PCOS patients have high androgen levels, which affect normal follicle development. When they do not respond to CC+HMG treatment, DXM 0.25-0.5mg or prednisone 5mg orally can be added to CC+HMG treatment, starting on the second day of menstruation, qd×7-10d. It is also recommended to stop using it only when pregnancy is confirmed continuously.
GnRH is a decapeptide hormone secreted by hypothalamic neurons, which is released from the synaptic terminals into the pituitary portal system to stimulate the secretion of FSH and LH by anterior pituitary cells. in the normal menstrual cycle, GnRH is secreted in a pulsatile manner, and its frequency and amplitude vary with the menstrual cycle; the frequency is fast in the follicular phase, about 90 This cyclic variation of GnRH is extremely important for the pulsatile release of FSH and LH from the pituitary gland, which can regulate FSH and LH secretion in two ways, i.e. ascending and descending regulation, also known as bidirectional response. Ascending regulation means that small doses of GnRH stimulate the pituitary gland to produce Gn, and the clinical treatment of hypothalamic anovulation is based on this principle. Descending regulation refers to the suppression of pituitary secretion by high doses or continuous use of GnRH. The principle of descending regulation is that under the effect of high dose of GnRH, desensitization of pituitary cells occurs, their receptors cannot continue to bind to GnRH, and the number of receptors is reduced, thus inhibiting the secretory function of pituitary gland, and low Gn hypogonadism occurs, also known as pharmacological pituitary resection. It is used clinically to treat sex hormone-dependent disorders such as uterine fibroids, endometriosis, and precocious puberty.
GnRH needs to be applied in combination with HMG, FSH and HCG to induce ovulation, which is mainly used in the process of inducing superovulation in assisted conception techniques, and the commonly used protocols are as follows.
A. GnRH long-cycle down-regulation protocol: GnRH is first applied to desensitize the pituitary-ovary, and then Gn is applied to promote ovulation, which can purposely control and promote the synchronized development and maturation of multiple follicles in the ovary, inhibit endogenous LH peaks, and deter premature follicular luteinization and premature egg maturation.
Nasal Buserelin 500 μg, qd, or 150 μg, tid; or 600 μg once daily subcutaneously is usually started late in the menstrual cycle, i.e., mid-luteal phase (approximately day 21 of the menstrual cycle) prior to the desired ovulation treatment. After 14 days of GnRHa, that is, after achieving pituitary hyporegulation (pituitary hyporegulation criteria are <10 mm in diameter of both ovarian follicles, LH <5 IU/L, E2 <50 pg/ml), ovulation promotion was switched to Gn, that is, day 5 of the next cycle, and GnRHa was maintained until ovulation. the starting dose of FSH was 150-225 IU/d, and after 3 days, it could be switched to HMG 225IU/d (helps maturation of eggs and growth of endometrium), which can be increased by 75IU/d every 5 days according to follicle growth. 10,000IU of HCG is given intramuscularly when at least 2 follicles are ≥15mm in diameter. About 36h after HCG injection, eggs were retrieved by puncture under vaginal ultrasound guidance. This protocol makes follicle development completely dependent on exogenous Gn stimulation, thus avoiding excessive endogenous LH levels or inappropriate LH peaks.
B. GnRH short-cycle descending regimen: Gn is given on the 2nd day of menstruation, while GnRH-a is started until it is discontinued at the time of HCG injection. This regimen is beneficial for follicle development and improving egg quality.
C. GnRH ultra-short-cycle downregulation regimen: Buserelin 500 μg, qd, for 3 days is started on days 2, 3 and 4 of menstruation, while HMG is started on day 3 of menstruation and HCG is injected after follicle maturation (same as long regimen).
D. Double downregulation regimen: take oral short-acting contraceptives Mendocin or Mafulon in the previous cycle of the egg retrieval cycle, and when 4-5 pills are left (meaning effective white pills), receive GnRH long-cycle downregulation regimen. Oral contraceptives are beneficial in improving endometrial tolerance and may increase follicular recruitment and are used in patients with irregular or anovulatory menses. For PCOS patients with elevated androgens, Dain 35 can be used, which has a hypoandrogenic effect.
(3) Treatment of hyperprolactinemia.
In these patients, blood PRL is higher than normal and ovulation is usually possible after bromocriptine treatment. If there is no ovulation, add HMG or CC to induce ovulation at the same time.
Use: Start with a small dose of 1.25 mg/d with dinner. Depending on its therapeutic effect and tolerability, increase the dose once a week, such as 1.25mg, bid, 2.5mg, bid, and so on. The usual daily dosage is 5-7.5 mg. Indications for effective treatment are cessation of overflow, return to normal PRL, regular menstruation, ovulation and pregnancy. For those who cannot tolerate serious side effects, the effect of vaginal administration is the same as that of oral administration. The dose of PRL should be adjusted according to the level of PRL until the drug is stopped. To prevent the rebound of PRL after discontinuation, the dose should be gradually reduced.
If necessary, increase the dosage of CC, and only if it is not effective, switch to HMG. Although there is no evidence that bromocriptine is harmful to the fetus, it should be discontinued immediately after pregnancy is confirmed.
Side effects of bromocriptine occur mainly at the beginning of treatment and at higher doses. The overall incidence of side effects is 40.8%, and 5%-10% of treatment discontinuation is due to side effects. The common side effects are gastrointestinal reactions, nausea, vomiting, loss of appetite and constipation, dizziness, headache, vision changes, and occasionally hallucinations and syncope when the dose is too high. These side effects are dose-dependent and may disappear on their own after dose reduction or discontinuation.