Week 5- Sex Hormones Flashcards
Define puberty
The maturation of reproductive organs causing production of sex steroids, development of secondary sexual characteristics and attainment of capability to reproduce
How are the stages of puberty classed?
The Tanner staging scale
What is breast development known as?
Thelarche
What is growth of pubic hair known as?
Pubarche
What is gonadarche?
Activation of gonads by HPG axis
What is adrenarche?
Adrenal androgen production
What are main 2ndary sexual characteristics for girls?
Breast development
Hair growth (pubic and axiallary)
Sweat gland composition
Changes to external genitalia
What are main 2ndary sexual characteristics for boys?
Deepening of voice
Hair growth (pubic then axillary/facial)
Sweat gland composition
Changes to external genitalia
What is the first sign of puberty for girls and the late sign?
First sign: Thelarche
Late sign: Menarche
What is the testicular size for boys when they are prepubertal vs when they are adults?
Prepubertal: < 4mls
Adult: > 15mls
During puberty how is GnRH released?
Nocturnally in pulses
During adulthood how is GnRH released?
In pulses throughout the day
When is the normal onset of puberty for girls?
8-13 yrs
When is the normal onset of puberty for boys?
9-14 yrs
What is early puberty known as and is it more common in girls or boys?
Precocious puberty, more common in girls
What is late puberty known as and is it more common in girls or boys?
Delayed puberty, more common in boys
How many years approx after thelarche does menarche occour?
2.3 yrs
After what age is amenorrhea regarded abnormal?
16 yrs
What happens during the follicular phase?
FSH rises 2/3 follicles start to grow Follicles produce E2 and inhibin This reduces FSH via -ve feedback Non dominant follicles undergo atresia A dominant Graafian follicle emerges Theres a switch to positive feedback by E2 Induces a LH surge Ovulation
What 2 hormones does the corpus luteum produce?
Progesterone
Oestradiol
What is the name of the phase after ovulation?
Luteal phase
What chemical is tested for to see if someone has ovulated?
Midluteal D21 progesterone
What phase is the endometrium in during ovulation?
Proliferative phase
What phase is the endometrium in during the luteal pahse?phase?
Secretory phase
What effect does hCG have on the corpus luteum?
Causes continual production of progesterone and oestradiol, maintaining the uterine lining allowing pregnancy to continue
What time elapses between GnRH pulses during the follicular phase?
Every 90-120 mins
What time elapses between GnRH pulses during the luteal phase?
Every 180- 240 mins
What is hypogandism in males vs females?
Males: decreased testosterone
Females: decreased oestrogen
What does the ‘primary’ in primary hypogonadism signify?
Direct damage to the gland eg testes/ovaries
What happens in hypogonadism?
Decreased testosterone/oestrogen causes reduced negative feedback to GnRH or the pituitary gland causing increased levels of FSH/LH
What happens in menopause?
Low oestrogen causing eventual increase in FSH/LH as well as low E2 and low inhinbin
What are some symptoms of menopause?
Skin dryness Hair thinning Hot flushes/sweating Sleep distrubance Osteoporosis Sexual dysfunction Weight gain Amenorrhea Climateric (irregular periods in the years approaching menopause)
What is the treatment for menopause?
Oestrogen replacement (HRT)
This stimulates the endometrium, if progesterone is added the endometrium is intact to prevent risk of endometrial hyperplasia/cancer
At what age does menopause occur?
45-55 years (51 is median)
Menopause before what age qualifies as premature menopause?
Less than 40 years old
What else is premature menopause known as?
Premature ovarian insufficiency
What are some causes of premature ovarian insufficiency?
Autoimmune
Genetic (fragile X syndrome/turners syndrome)
Cancer therapy
What time of day is testosterone measured and why?
Before 11 am as it has a diurnal rythm
What are some symptoms of testosterone deficiency?
Sexual dysfunction
Hair growth (ask about frequency of shaving)
Lower energy levels
Mood disturbance
Body composition (increased fat/reduced muscle mass/ gynaecomastia ie breast enlargement)
How many stages are there in the Tanner staging scale?
5 (I-V)
What hormone causes 2ndary sexual characteristics on females?
Oestradiol
What hormone causes 2ndary sexual characteristics on males?
Testosterone
When does adrenarche occur in females?
6-9 yrs
When does adrenarche occur in males?
7-10 yrs
When do females normally have a growth spurt?
11-13 years
When do males normally have a growth spurt?
13-15 yrs
What hormone markedly increases during adrenarche?
DHEA
What 2 hormones markedly increase during gonardarche? Which of the 2 is higher?
LH and FSH, with FSH always being higher
What is mini puberty?
When there is activation of the HPG axis in the first 6 months of life leading to oestrodiol/testosterone production depending on wether you are male or female
What is the condition that arises when mini puberty doesnt occour? How does it manifest in males?
Cowman’s syndrome, causes males testes not to drop properly and they have a micropenis
How many follicles start to grow in the follicular phase of the menstrual cycle?
2-3
What do developing follicles produce in the follicular phase of the menstrual cycle?
E2 and inhibin B
What negative feedback response do E2 and inhibin B cause during the follicular phase of the menstrual cycle?
Reduce FSH production
What is the name of the process undergone by non dominant follicles in the follicular phase of the menstrual cycle?
Atresia
What is the dominant follicle called in the follicular phase of the menstrual cycle?
Graafian follicle
What chemical rises in level after the emergence of the Graafian follicle in the follicular phase of the menstrual cycle? What effect does it have?
E2, it causes positive feedback inducing an LH surge
Which chemical in the follicular phase causes a surge in LH?
E2
What hormone provides evidence of ovulation?
Midluteal D21 progesterone
What type of release is GnRH released by?
Pulsatile
What happens when GnRH is released constantly instead of in pulses?
Decreased LH/FSH is secreted
What happens to LH/FSH/E2 and testosterone levels in hypogonadism?
LH/FSH levels rise
E2/testosterone levels fall
What is secondary hypogonadism?
Due to a problem with the pituitary gland eg pituitary tumor/high prolactin
What happens to levels of LH/FSH/E2/testosterone in secondary hypogonadism?
Low or normal LH/FSH
Low E2/testosterone
What is the main marker of ovarian reserves? How does it indicate ovarian reserves?
Anti Mullerian hormone, it peaks in early adult life and is very low at menopause
Where is anti mullerian hormone synthesised?
In sertoli cells in the ovary
How does testosterone circulate?
38% bound to albumin
60% bound to SHBG
2% free/unbound
What is the difference between albumin and SHBG in relation to testosterone binding?
Albumin binds weakly so testosterone is bioavailable
SHBG binds strongly so the testosterone is unavailable
What happens to the way testosterone circulates as men get older?
Less testosterone circulates freely, more is bound to SHBG so free testosterone is reduced
When is it ideal to measure testosterone and why?
Measure it fasting as levels can fall as much as 20% with sugar
What enzyme converts testosterone to oestrogen?
Aromatase
What enzyme converts testosterone to dihydrotestosterone?
5 alpha reductase
How is dihydrotestosterone different to testosterone?
DHT is a more potent ligand for androgen receptors
Where is aromatase found?
Adipose tissue Adrenal glands Ovaries (granulosa cells) Testes (sertoli cells) Brain Bone Skin
Where is 5 alpha reductase found?
Testes (seminal vesicle, epididymis)
Prostate
Skin
Liver
Why may there be low levels of testosterone?
Primary causes: damage to the testes due to trauma, mumps etc
Secondary causes: damage to the pituitary due to head trauma, pituitary adenoma (hyperprolactinemia)
Interference with pulsatile secretion: due to drugs (depressent ones eg citalopram, alcohol, heroine, cannabis)
When a patient presents with low testosterone, why should you examine 2ndary sexual characteristics?
If they are absent, the low testosterone is likely due to genetic conditions
What questions would help when diagnosing someone with low testosterone?
Have you noticed any changes in your vision?
Are you a drug user?
Do you drink frequently? If so how much
Have you had any infections recently?
Have you experienced a lot of stress recently?
Have you had any milk expression?
What happens if someone is deficient in 5 alpha reductase?
2ndary male sexual characteristics are not driven, baby is born looking completely female but has male reproductive organs internally. Voice may deepen etc in early teens, they wont get a period, may start to feel as if they are a boy and present with symptoms
