Sex Hormones During Life Flashcards
Puberty
Maturations of the reproductive organs
Production of sex steroids - oestradiol and testosterone
Develop secondary sexual characteristics
Attain capability to reproduce
What is the main measure of puberty in girls
Thelarche ( breast development)
What is the main measurement of male puberty
Genitalia ( testicular volume in boys)
What is used to measure the puberty in both males and females
Pubarche
Gonadarche
Activation of gonads by HPG axis
Thelarche
Breast development
Menarche
Menstrual cycles
Spermaeche
Spermatogenesis
Adrenarche
Adrenal androgen production
Pubarche
Pubic hair
Secondary sexual characteristic in girls
Oestradiol : Breast development Hair growth ( pubic, axillary) Sweat gland composition - skin oiliness / acne Changes to external genitalia
Secondary sexual characteristic in men
Testosterone - deepening of voice Hair growth - Pubic, axillary , facial Sweat gland composition - skin oiliness / acne Changes to external genitalia
Onset of puberty in girls
8-13 yrs
Onset of puberty in boys
9-14 yrs
Look at the puberty sequence of events slide
Puberty sequence of pubertal events diagram
First thing that occurs for puberty to take place
Activation of the GnRH axis
Gonadarche
In foetus there is a mini puberty so especially in boys what happens is that there is testicular descent, pencils length , Sertoli cell maturation and behavioural effects
Then quiescence of HPG axis
Then increased nocturnal GnRH pulsatility
The normal pulsating GnRH secretion
Who does delayed puberty occur more often in
Boys than girls
Who does precocious puberty occur more often in
Girls
Sequence of puberty in girls
Thelarche
Growth spurt
Pubarche
Menarche
Sequence of events in boys
Genitalia
Pubarche
Growth spurt
Spermarche
Primary ammenorrhea
When periods start later than 16 years or do not occur
Secondary amenorrhea
Common for periods to be irregular/ involuntary for the first 18 months
Periods start and then stop for at least 3-6 months
What is the most commonest physiological cause of secondary amenorrhea in women
Pregnancy
Amenorrhea
Absence of periods
- no periods for at least 3-6 months
Or up to 3 periods per year
Oligomenorrhea - few periods
Irregular or infrequent periods which are more than 35 day cycles
4-9 cycles per year
1st stage of follicular phase
FSH ( follicular stimulating hormone ) rises which causes 2-3 follicles to grow
Second phase of menstrual cycle
2-3 follicles start to grow
Third phase of menstrual cycle
Follicles produce estradiol and inhibin B
Inhibin B causes negative feedback on pituitary gland , estradiol at low levels can cause negative feedback on the HPG axis - these all act to decrease the HPG axis and decrease FSH back down
What is the 4 th step of menstrual cycle
FSH is reduces by E2 and inhibin B by negative feedback
What is the 5th step of the menstrual cycle
The FSH window is restricted and the non dominant follicles undergo atresia
However the largest follicle typically needs less FSH to grow as it grows larger and therefore this then develops into the dominant grafian follicle
Step 7 of menstrual cycle
The levels of oestradiol increase as the dominant graffiti follicle continues to secrete more oestradiol
Step 8 of menstrual cycle
The oestradiol switches to positive feedback on pituitary gland
Step 9 of the menstrual cycle
LH surge is induced by high E2 and positive feedback and this causes high LH
Step 10 of ovulation
Ovulation is caused
Literal phase
Corpus leuteum produces progesterone and oestradiol acts on endometrium to make it better for pregnancy
Endometrium ; uterine cycle
1) menstrual phase
2) proliferative phase / oestradiol - endometrium lining regrows which causes the growth of new epithelial cells
Gland proliferation
Increase in stromatolites / arteriolar
3) secretory phase ( progesterone ) - transformation of uterine layer to be receptive for implantation . Increased volume of stromatolites cells > thick spongy lining
Cork screw shaped glands secreting glycogen
Coiling and lengthening of spinal arteries
What hormone does the embryo produced and how does this cause on corpus leuteum
Secreted B-HCG which acts on LH receptors on corpus Lyceum and maintains the production of progesterone and oestradiol during pregnancy which maintains the endometrium lining
If no embryo is implanted then no beta HCG is produced which means that the corpus luteum dies off and no progesterone and oestradiol is produced
When in non pulsation GnRH used ( normal GnRH secretion is pulsatile)
If nonpulsatile you get a decrease in GnRH and this decreases LH and FSH which can be used to treat prostate cancer for example as cancer cells need LH and FSH to divide
Hypogonadism
Decreased oestrogen in woman
Decreased testorone in. Man
Possible causes of hypogonadism
Problems affecting pituitary gland or the testes or ovaries or the hypothalamus
Primary hypogonadism
Problem with the testes or the ovaries
You have low E2 or Testosterone but have high LH/FSH
Examples of causes of primary hypogonadism in man
Infection - e.g. mumps / trauma/ cancer of testes
What is the commonest physiological cause of primary hypogonadism in women
Menopause.
Low E2 ,
High LH/FSH
Low inhibin
Secondary hypogonadism / hypogonadotropjic hypogonadism
Low or normal LH/FSH
Low E2/ Testosterone
Possible causes of secondary hypogonadism
Pituitary tumour / high prolactin- prolactinoma
Menopause symptoms
Due to lack of estradioj
Skin dryness/hair thinning Hot flushes / sweating / sleep disturbances Mood disturbance Osteoporosis Sexual dysfunction Weight gain Amenorrhea Cessation of fertility Climacteric
Peri menopausal
Within 1 year of LmP
Post menopausal
After 1 he of menopause
Treatment of menopause
Osteogenesis replacement ( HRt)
Oestrogen stimulates the endometrium but to make sure that the endometrium doesn’t grow too much, you add progesterone which reduces risk of endometrial hyperplasia/ cancer
What is ovarian reserve
Number of eggs that you can have in the ovaries before you go to menopause
Blood test to find ovarian reserve
Blood test - measure level of anti mullerian hormone - peaks in early adult life
Early menopause is also called
Premature ovarian insufficiency
Symptoms of PoI
Same symptoms as per menopause but still producing a bit of oestrogen , conception may occur
Diagnosis of POI
High FSH > 25 iU/L on at least 2 occasions 4 weeks apart
Causes of POI
Autoimmune
Genetic - fragile X syndrome / Turner syndrome
Cancer therapy - radio / chemo therapy in the past
Is there an equivalent of menopause in men
Late onset hypogonadism
SHBG
Sex hormone binding globulin which binds to testosterone and makes it not available
Albumin
Binds to testosterone but weakly and so the testosterone is bioavailable
Free testosterone
With age there is a decrease in free testosterone and increase in SHBG
When and how is testosterone measured
In the morning at fasting as glucose can decrease testosterone levels
Symptoms of testosterone deficiency
Sexual dysfunction
Erectile dysfunction
Hair growth - decreased frequency of having
Low energy levels
Mood disturbance
Body composition - increased fat/reduced muscle mass
Gynaecomastia ( breast enlargement in man)
Spermatogenesis - high levels of intra testicular testosterone needed
Bone health - via conversion to oestrogen
5 alpha reductase
Converts testosterone to di hydro testosterone ( DHT) and stronger androgen than testosterone and more potent ligand for androgen receptor
Aromatase
Converts testosterone to Oestrogens
What can increase Oestrogens
Age Obesity Insulin Gonadotrophins Alcohol
Breast cancer
Can use aromatase inhibitor like anstfozole which decreases the testosterone to oestrogen
Prostate cancer
5 alpha reductase inhibitor
E.g. finasteride
