Reproductive Endocrinology, Hypothalamic-Pituitary-Gonadal Axis, GnRH, FSH, LH, Estradiol, Estrone, Estriol, Progesterone, Androgens, Testosterone, Anabolic Steroids, Oral Contraceptives, Progesterone-Only Contraceptives, SERM Therapy, Vaginal Ring, Trans

Reproductive Endocrinology, Hypothalamic-Pituitary-Gonadal Axis, GnRH, FSH, LH, Estradiol, Estrone, Estriol, Progesterone, Androgens, Testosterone, Anabolic Steroids, Oral Contraceptives, Progesterone-Only Contraceptives, SERM Therapy, Vaginal Ring, Transdermal Patch, Levonorgestrel IUD, Maternal Pharmacokinetics, Placental-Fetal Drug Transfer, PDE5 Inhibitors, Finasteride, Dutasteride, Alpha-Adrenergic Antagonists, Drug Interactions, Pregnancy Safety, Pharmacologic Adverse Effects, Ovulation Induction, Fertility Management, Sexual Dysfunction, BPH, Endometriosis, Menopause Management Exam Questions Verified and Provided with Complete A+ Graded Rationales Latest Updated 2026 GnRH hormones Released from the hypothalamus Responsible for regulating the anterior pituitary release of FSH and LH Follicule stimulating hormone FSH Females = follicule development/preparation and estrogen production Males = promotes sperm development Luteinizing hormone (LH) Stimulates ovulation Females = stimulates ovulation and secretion of both estrogen and progesterone by the ovaries Males = production of testosterone Estrone (E1) Weak estrogen produced by body fat Menopausal estrogen Estriol (E3) Weak estrogen produced by placenta Estrogen in pregnancy Estradiol (estradiol-17, E2) Major secretory product of the ovary Potent estrogen produced by follicular cells Primary "reproductive" estrogen When eggs are gone (age 51), estradiol is gone Estrogen physiology CNS: both alpha and beta receptors Alpha: brain, breasts, endometrium of uterus Beta: blood - stimulate clotting, increase HDL, decrease LDL, increase triglycerides Bone: prevents bone absorption Progesterone - uterus Inhibits endometrial proliferation Promotes spiral artery formation in uterus Promotes endometrial glandular activity Thick, white cervical mucus to inhibit sperm entry into uterus during luteal phase Progesterone - breasts Increase number and size of milk cells Increase lobular formation in breast Does not inhibit lactation Progesterone - other Inhibits female facial hair growth High amounts decrease bone density by opposing estrogen Increases LDL Decreases HDL Decreases triglycerides Coverts kidney desoxycorticosteroid GnRH agonists Gonadotropin-releasing hormone - responsible for regulating the release of FSH and LH from the pituitary gland Initial use causes release of LH and FSH that leads to a "flare effect" response in first 2 weeks, but sustained use shuts it down and interrupts ovarian and testicular steroid production Sustained use stops reproductive cycles = improves endometriosis Uses: endometriosis, shrink uterine fibroids, assisted reproductive therapy, prostate cancer Leuprolide, Beserelin, Nafarelin, Histrelin, Goserelin, Triptorelin SE: menopause symptoms (e.g. flushing), h/a, insomnia, sweating FSH related medications Follitropin alfa, follitropin beta, follitropin delta Indications: stimulate ovum production typically in women having in-vitro fertilization, spermatogenesis or induction in men SE: multiple ovulation, ovarian cysts, ovarian hyperstimulation syndrome SERM therapy Selective estrogen receptor modulator Weak estrogenic activity - blinds hypothalamus-pituitary to circulating estrogen = increases FSH / LH = ovarian stimulation Indications: ovarian induction, PCOS Clomiphene citrate (50mg for 5 days, day 3-5 of cycle, intercourse every other day, ovulation predictor kit) SE: twins, hot flashes, visual disturbances, h/a, abdominal bloating, nausea, ovarian enlargement Oral contraceptives MOA: low levels of estrogens can prevent LH thus preventing ovulation; thickens cervical mucus making it difficult for sperm to move; prevention of implantation (abortifacient function) Efficacy largely dependent on adherence Those that benefit: Dysfunctional uterine bleeding, endometriosis, dysmenorrhea, mittlechmerz, hirsutism, acne, hypothalamic amenorrhea - decreases osteoporosis, control of bleeding, functional ovarian cysts, premenstrual syndrome Those who should not receive: preg, breastfeeding, smoking and over 35, undiagnosed bleeding, hypertension, diabetes, DVT, h/a, cva, breast cancer or endometrial carcinomas oral contraceptives advantages protection from: