2026 MENSTRUAL CYCLE, MENOPAUSE
& RELATED DISORDERS STUDY GUIDE
QUESTIONS AND VERIFIED CORRECT
ANSWERS 100% PASS
Gonadotropin-Releasing Hormone (GnRH)
GnRH is a hypothalamic hormone released in a pulsatile manner that stimulates anterior pituitary
secretion of LH and FSH to regulate puberty and fertility, with clinical significance because
continuous GnRH suppresses sex hormone production and is used therapeutically.
Testosterone
Testosterone is an androgen produced primarily by Leydig cells of the testes that drives male
sexual development, spermatogenesis, and libido while also increasing erythropoiesis, muscle
mass, bone density, metabolic rate, and mood, explaining higher hematocrit in males and risks of
polycythemia with therapy.
Estrogen (Estradiol)
Estrogen is a sex steroid produced mainly by the ovaries that regulates female sexual
development, endometrial proliferation, and ovulation (via positive feedback causing the LH
surge) while also preserving bone density, cardiovascular health, lipid balance, and cognitive
function.
Estrogen promotes endometrial proliferation, secondary sexual characteristics, bone density
maintenance, and feedback regulation of FSH/LH to coordinate the menstrual cycle.
,Progesterone
Progesterone is a hormone secreted by the corpus luteum and placenta that stabilizes the
endometrium for implantation and pregnancy while also exerting thermogenic, sedating, and
smooth-muscle–relaxing effects, contributing to fatigue, constipation, and bloating.
Progestin (progesterone) stabilizes the endometrium after ovulation, prepares it for implantation,
thickens cervical mucus, suppresses LH, and its withdrawal triggers menstruation.
estrogen vs progestin
Estrogen drives endometrial growth and can worsen bleeding or hyperplasia when unopposed,
whereas progestins counteract estrogen by stabilizing or thinning the endometrium, which is why
oral contraceptives use progestins (± estrogen) to regulate bleeding, suppress ovulation, and treat
disorders like AUB, PCOS, and endometriosis.
Inhibin B
Inhibin B is a hormone made by the testes in men and ovaries in women that acts like a brake on
FSH, telling the brain “we’re making enough sperm or eggs right now” so hormone levels stay
balanced during reproduction.
Androgen-Binding Protein (ABP)
Androgen-binding protein (ABP) is made by Sertoli cells and works by holding testosterone in
the seminiferous tubules, keeping levels high where they’re needed to support normal sperm
production.
,Dehydroepiandrosterone (DHEA)
DHEA is a weak adrenal androgen that helps cause pubic and axillary hair, body odor, and acne
and serves as a building block for estrogen and testosterone, while DHEA-S is its more stable
circulating form, used clinically to assess adrenal androgen excess and also contributes to
secondary sexual hair development.
REQUIREMENTS FOR A NORMAL MENSTRUAL CYCLE
1. Intact Hypothalamic–Pituitary–Gonadal (HPG) Axis
A normal menstrual cycle requires an intact HPG axis with pulsatile GnRH release leading to
coordinated LH and FSH secretion and appropriate estrogen and progesterone production.
2. Ovulation
Ovulation is required to form a functional corpus luteum, which produces progesterone
necessary for luteal phase stability and normal timing of menses.
3. Normal Endometrial Response
The endometrium must respond appropriately to estrogen-driven proliferation and progesterone-
mediated secretory transformation to allow predictable shedding during menstruation.
Disruption at Any Level → Menstrual Disorder
Disruption at the hypothalamic, pituitary, ovarian, or endometrial level alters hormonal signaling
or tissue response and results in amenorrhea, oligomenorrhea, abnormal uterine bleeding, or
anovulatory cycles.
, Phase I menstrual cycle
menstruation and follicular phase!
(occurs due to progesterone withdrawal)
- start of the follicular phase, progesterone and LH reach their lowest point and in response the
pituitary gland increased FSH to mature the ovarian follicles & for selection of the dominant
follicle! An increase in FSH begins 2 days before menstruation. FSH causes the oocyte to secrete
estradiol which stimulates the pituitary to decrease FSH and increase LH
Day 1 is defined as the first onset of bleeding of menstruation and follicular phase
Menstruation = endometrial lining is sloughed off in response to progesterone withdrawal
Development of a new follicle during the follicular phase with renewal of the endometrial lining
(hence sloughing) in preparation for implantation of a potential embryo post fertilization
Phase II: ovulation (LH surge on days 11-13 triggers ovulation)
Dominant follicle selected with help of FSH → estradiol secreted by oocyte (helps the follicle
mature )→ stimulates pituitary to release LH (causes oocyte to be expelled from the follicle) →
ovulation → oocyte converted into corpus luteum → secretes progesterone for the rest of the
cycle → decrease in FSH and LH secretion from the pituitary
Phase III: luteal phase (estradiol predominance switches to progesterone predominance and is
sustained for 11 days)
& RELATED DISORDERS STUDY GUIDE
QUESTIONS AND VERIFIED CORRECT
ANSWERS 100% PASS
Gonadotropin-Releasing Hormone (GnRH)
GnRH is a hypothalamic hormone released in a pulsatile manner that stimulates anterior pituitary
secretion of LH and FSH to regulate puberty and fertility, with clinical significance because
continuous GnRH suppresses sex hormone production and is used therapeutically.
Testosterone
Testosterone is an androgen produced primarily by Leydig cells of the testes that drives male
sexual development, spermatogenesis, and libido while also increasing erythropoiesis, muscle
mass, bone density, metabolic rate, and mood, explaining higher hematocrit in males and risks of
polycythemia with therapy.
Estrogen (Estradiol)
Estrogen is a sex steroid produced mainly by the ovaries that regulates female sexual
development, endometrial proliferation, and ovulation (via positive feedback causing the LH
surge) while also preserving bone density, cardiovascular health, lipid balance, and cognitive
function.
Estrogen promotes endometrial proliferation, secondary sexual characteristics, bone density
maintenance, and feedback regulation of FSH/LH to coordinate the menstrual cycle.
,Progesterone
Progesterone is a hormone secreted by the corpus luteum and placenta that stabilizes the
endometrium for implantation and pregnancy while also exerting thermogenic, sedating, and
smooth-muscle–relaxing effects, contributing to fatigue, constipation, and bloating.
Progestin (progesterone) stabilizes the endometrium after ovulation, prepares it for implantation,
thickens cervical mucus, suppresses LH, and its withdrawal triggers menstruation.
estrogen vs progestin
Estrogen drives endometrial growth and can worsen bleeding or hyperplasia when unopposed,
whereas progestins counteract estrogen by stabilizing or thinning the endometrium, which is why
oral contraceptives use progestins (± estrogen) to regulate bleeding, suppress ovulation, and treat
disorders like AUB, PCOS, and endometriosis.
Inhibin B
Inhibin B is a hormone made by the testes in men and ovaries in women that acts like a brake on
FSH, telling the brain “we’re making enough sperm or eggs right now” so hormone levels stay
balanced during reproduction.
Androgen-Binding Protein (ABP)
Androgen-binding protein (ABP) is made by Sertoli cells and works by holding testosterone in
the seminiferous tubules, keeping levels high where they’re needed to support normal sperm
production.
,Dehydroepiandrosterone (DHEA)
DHEA is a weak adrenal androgen that helps cause pubic and axillary hair, body odor, and acne
and serves as a building block for estrogen and testosterone, while DHEA-S is its more stable
circulating form, used clinically to assess adrenal androgen excess and also contributes to
secondary sexual hair development.
REQUIREMENTS FOR A NORMAL MENSTRUAL CYCLE
1. Intact Hypothalamic–Pituitary–Gonadal (HPG) Axis
A normal menstrual cycle requires an intact HPG axis with pulsatile GnRH release leading to
coordinated LH and FSH secretion and appropriate estrogen and progesterone production.
2. Ovulation
Ovulation is required to form a functional corpus luteum, which produces progesterone
necessary for luteal phase stability and normal timing of menses.
3. Normal Endometrial Response
The endometrium must respond appropriately to estrogen-driven proliferation and progesterone-
mediated secretory transformation to allow predictable shedding during menstruation.
Disruption at Any Level → Menstrual Disorder
Disruption at the hypothalamic, pituitary, ovarian, or endometrial level alters hormonal signaling
or tissue response and results in amenorrhea, oligomenorrhea, abnormal uterine bleeding, or
anovulatory cycles.
, Phase I menstrual cycle
menstruation and follicular phase!
(occurs due to progesterone withdrawal)
- start of the follicular phase, progesterone and LH reach their lowest point and in response the
pituitary gland increased FSH to mature the ovarian follicles & for selection of the dominant
follicle! An increase in FSH begins 2 days before menstruation. FSH causes the oocyte to secrete
estradiol which stimulates the pituitary to decrease FSH and increase LH
Day 1 is defined as the first onset of bleeding of menstruation and follicular phase
Menstruation = endometrial lining is sloughed off in response to progesterone withdrawal
Development of a new follicle during the follicular phase with renewal of the endometrial lining
(hence sloughing) in preparation for implantation of a potential embryo post fertilization
Phase II: ovulation (LH surge on days 11-13 triggers ovulation)
Dominant follicle selected with help of FSH → estradiol secreted by oocyte (helps the follicle
mature )→ stimulates pituitary to release LH (causes oocyte to be expelled from the follicle) →
ovulation → oocyte converted into corpus luteum → secretes progesterone for the rest of the
cycle → decrease in FSH and LH secretion from the pituitary
Phase III: luteal phase (estradiol predominance switches to progesterone predominance and is
sustained for 11 days)
