A 34-year-old woman with polycystic ovary syndrome comes to the office with her husband for treatment of infertility. The patient has been unable to conceive despite having unprotected sexual intercourse several times a week for the past 2 years. Her menses are irregular and occur every 2-3 months, consistent with chronic anovulation. She does not use tobacco, alcohol, or illicit drugs. The patient takes no medications and has no allergies. BMI is 32 kg/m². Physical examination shows coarse hair on her chin and abdomen. The patient is initially prescribed clomiphene therapy but fails to conceive. She then receives ovulation induction therapy with a short course of menotropins followed by a single injection of human chorionic gonadotropin (hCG). The use of hCG therapy primarily mimics which of the following physiologic events?

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11ec160b_3cbb_9436_9249_0d7ddc71bd1f_MD0001_00 Women of reproductive age experience cyclic hormonal changes of the hypothalamus-pituitary-ovarian axis that normally manifest as monthly ovulation and menstrual bleeding. Pulsatile gonadotropin-releasing hormone from the hypothalamus causes intermittent secretion of FSH and LH from the pituitary. FSH and LH are responsible for the development of the ovarian follicle and ovulation, respectively. The normal menstrual cycle consists of the follicular and luteal phases. Following the onset of menstruation, FSH stimulates one or more dominant follicles to form in one of the ovaries (follicular phase). FSH also stimulates estrogen production from the ovaries. As the follicular phase advances, a progressive rise in serum estradiol is seen. High estrogen levels in the late follicular phase have a positive feedback effect on LH production, resulting in an LH surge. Ultimately, the LH surge causes the rupture of the dominant follicle, leading to extrusion of an ovum (ovulation). Failure of ovulation (eg, anovulation in polycystic ovary syndrome) is a common cause of infertility. Treatment options include the administration of drugs that act like FSH and LH. Menotropin (human menopausal gonadotrophin) therapy mimics FSH and triggers the formation of a dominant ovarian follicle. When the follicle appears mature, exogenous human chorionic gonadotropin (hCG) is administered. The alpha subunit of hCG is structurally similar to LH and therefore simulates the LH surge by inducing ovulation. (Choice A) Estrogen levels continue to increase progressively during the follicular phase. Peak estrogen levels are seen just before the LH surge. (Choice B) The effect of hCG therapy is analogous to the LH surge. Menotropin therapy mimics the FSH surge, which is very small compared to the large LH surge. (Choice D) Progesterone secretion increases following ovulation with the formation of the corpus luteum. Peak progesterone levels are seen in the mid-luteal phase. (Choice E) Prolactin increases substantially during pregnancy and peaks at delivery to prepare the breast for lactation. Elevated prolactin levels lead to anovulation (eg, lactational amenorrhea). Educational objective: Anovulation is a common cause of infertility. Menotropin (human menopausal gonadotropin) is a treatment option that acts like FSH and triggers the formation of a dominant ovarian follicle. Ovulation is then induced by administration of human chorionic gonadotropin, which mimics the LH surge. __________ References: Ovulation triggers in anovulatory women undergoing ovulation induction. (http://www.ncbi.nlm.nih.gov/pubmed/24482059)

A 34-Year-Old Woman with Polycystic Ovary Syndrome Comes to the Office