Hormonal Control of the Menstrual Cycle Flashcards
What hormone does the hypothalamus secrete for the menstrual cycle? In what manner?
GnRH
In pulses
Which hormones does GnRH trigger secretion of?
LH, FSH in pituitary
Which other hormones regulate LH, FSH release?
oestrogen
progesterone
How does oestrogen regulate LH, FSH
High oestrogen causes INCREASE in LH
Low oestrogen causes DECREASE in LH
How does progesterone regulate LH, FSH
High progesterone causes DECREASE in LH, FSH
Low progesterone causes INCREASE in LH, FSH
How does the COCP work on the menstrual cycle?
It maintains a constant serum oestrogen level that is in the negative feedback range
So there never is a surge in LH
What are the three stages in the uterine cycle?
Maria Prefers SAM
Menstruation
Proliferation
Secretory
What are the stages in the ovarian cycle?
Maria Forgets Of Laura
Menstruation
Follicular
Ovulation
Luteal
What stage of meiosis are oocytes stuck at from birth to puberty?
Prophase I
Describe the follicular stage
FSH rises
This stimulates some follicles to grow
The follicles produce androgens (from theca cells) which are then converted to oestrogen (from granulosa cells)
Oestrogen starts increasing, but it has a negative feedback effect on FSH, so FSH decreases
This causes follicular atresia except for the DOMINANT Follicle
What cells produce inhibin?
Granulosa cells
What does inhibit do?
further reduces FSH
What occurs in the ovulatory phase?
The dominant follicle keeps producing oestrogen until it switches to POSITIVE FEEDBACK on the pituitary
Oestrogen positive feedback on the pituitary causes LH surge (and smaller FSH surge)
Surge of LH and FSH stimulates resumption of meiosis and rupture of the ovarian follicle, so the oocyte is released
What occurs in the luteal phase?
The remaining theca cells and granulosa cells form the corpus luteum
The corpus luteum secretes lots of progesterone (and some oestrogen)
Progesterone inhibits FSH, LH
Ion the absence of beta hCG, corpus luteum regresses by luteolysis
Corpus luteum regresses to a corpus albicans, that does not make hormones
As there is a progesterone withdrawal, this results in menstruation
What occurs in the menstruations phase in the uterine cycle?
The endometrium is shedded (the stratum compactum and spongiosum)
The stratum basalts (deepest) remains through out the cycle
What occurs to the endometrium in the proliferative stage=
High oestrogen levels stimulate:
- thickening of the endometrium
- growth of endometrial glands
- formation of spiral arteries
- Thickening of cervixal mucous
How does the endometrial epithelium change during the proliferative phase?
From single columnar to pseudo stratified
Who does thickness of the endometrium change during the proliferative phase?
From 0.5mm to 3.5mm
What occurs to the endometrium in the secretly phase=
Progesterone forms the decidua Pinopodes appear (apical membrane projections of epithelial cells) making the endometrium receptive for implantations)
Endometrial glands become tortuous, spiral arteries grow, uterine glands secrete mucous
What is the role of leptin in puberty?
PERMISSIVE
So it is required for puberty to occur
Lack of leptin e.g. if very underweight means no puberty
What is the mean age of menarche?
12.8 years
What are physical changes in secondary sex characteristics?
Breast development
Pubic and axillary hair growth
Growth spurt
Menarche
What staging describes pubertal development?
Tanner staging
What is precocious puberty?
Puberty before the age of 9 in boys, 8 in girls
What is delayed puberty?
Lack of signs of secondary sex characteristics by the age of 14
What are causes of delayed puberty?
Central (due to no GnRH response)
- anorexia nervosa, excessive exercise
- chronic illness
- Kallmanns
Peripheral
- gonadal failure
- Turners
What is Kallmans syndrome?
Lack of GnRH production
What is the genotype in Turner’s
45X
What are presenting features of Turner’s
Short stature
Webbing of neck
Wide carrying angle
What conditions is Turners associated with
Aortic coarctation
IBS
Sensorineural/conduction deafness
Renall anomalies
What is 46XY gonadal dysgenesis due to
SRY gene mutation
What is swyer syndrome?
Complete gonadal dysgenesis - gonads remain as streak, do not produce any hormones
In absence of anti-mullarian hormone, mullein structures develop normally
Absence of testosterone means foetus does not virile
BUT GONADS DO NOT FUNCTION, so patient presents with delayed puberty
What s the most common cause of 46XY DSD?
Complete androgen insensitivity
What is primary amenorrhoea?
Failure to menstruate by the age of 16
What is secondary amenorrhoea?
Absence of menstruation for MORE THAN 6 MONTHS in a female of reproductive age that is not due to pregnancy, lactation or menopause
What is oligomenorrhoea?
Irregular periods at intervals >35 days with only 4-9 periods a year
What are key investigations for oligomenorrhoea?
pregnancy test Bloods - hormone levels (LH, FSH, prolactin, testosterone, TFT) TVUS MRI Karyotyping ...
What criteria are used to diagnose PCOS?
Rotterdam consensus criteria
Explain the Rotterdam consensus criteria
Must have 2 of the 3:
- Amenorrhoea/oligomenorrhoea
- clinical or biochemical hyperandrogegism m
- PCO on USS (12+ follicular cysts)
What diseases is PCOS associated with
T2DM
CV events
How can you manage PCOS?
Lifestyle advice, weight reduction
COCP - regulates menstruation
or cyclical oral progesterone (to induce bleeds)b
Ovarian drilling (may destroy ovarian storm, prompt ovulatory cycles)
How do you treat PCOS if sub fertility is an issue?
Clomiphene (SERM)
What is the function of FSH?
Recruitment and maturation of oocyte
Production of oestrogen
What is the function of LH?
Release of oocyte (ovulation)
Production of androgens
What is the function of oestrogen?
Thicken the endometrial lining
What is the function of progesterone?
Maintain the endometrial lining
How can you classify causes of amenorrhoea?
Hypothalamic
Pituitary
Ovarian
Endometrial
What are hypothalamic causes of amenorrhoea?
KALLMAN’S syndrome
Excessive exercise / weight loss / stress
Head injury
Hypothalamic lesion (craniopharyngioma, glioma)
Drugs (progestogens, HRT, dopamine agonist)
Systemic disorders (Sarcoid, TB)
What are pituitary causes of amenorrhoea?
- Adenoma (prolatinoma)
- Pituitary necrosis (Sheehan’s)
- Iatrogenic (surgery, radiotherapY)
- Congenital pituitary development failure
Why does Sheehan’s cause pituitary necrosis?
Because the pituitary increases in size during pregnancy
However the blood supply to it remains the same
So excessive blood loss (e.g. PPH) may cause infarction of the pituitary and therefore necrosis
What ovarian disorders cause amenorrhoea?
PCOS
What endometrial disorders cause amenorrhoea’
- Primary amenorrhoea: Haematocolpos (vagina filled with blood) if imperforate hymen/ malarian duct anomaly
- Secondary amenorrhoea: Asherman’
What investigations can be done for amenorrhoea?
Pregnancy test
Hormone levels (FSH, testosterone raised > PCOS)
Prolactin (Prolactinoma)
Thyroid
TVUSS, MRI
Hysteroscopy (Asherman’s, cervical stenosis)
Karyoptyping (e.g. Turner’s)
What are LH and FSH like in PCOS patients?
LH > FSH
This causes excess androgen production
What are complications of PCOS?
T2DM
CVD
Infertility
Endometrial hyperplasia
Why is endometrial hyperplasia in PCOS occurring and why is it dangerous?
Endometrial hyperplasia occurs because increased oestrogen levels in PCOS maintain a thickened endometrium. No bleeds mean that the endometrium is not shed
Ensure that there is at least 4 periods per year or induce them
This will prevent endometrial cancer
What are management options for PMS?
CONSERVATIVE:
- encourage healthy lifestyle
- improved nutrition
- regular exercise
- alcohol, caffeine limitation
- Exercise
MEDICAL: - COCP (bicycle/tricycle) - Transdermal oestrogen - GnRH analogue - SSRI - CBT for depression HYSTERECTOMY last reserve
