(endo) sex hormones during life Flashcards
(86 cards)
1
Q
what is puberty?
A
attaining the capability to reproduce:
- maturation of reproductive organs + development of secondary sexual characteristics
- production of sex steroids (e.g. oestradiol, testosterone)
2
Q
how are adolescents undergoing puberty staged?
A
using Tanner staging from I-V, where I is pre-pubertal and V is adult
1) in girls = thelarche (breast development)
2) in boys = testicular volume
3) both = pubarche (pubic hair)
3
Q
how is testicular volume determined in males?
A
using a prader orchidometer
4
Q
define gonadarche
A
activation of gonads by HPG axis
5
Q
define thelarche
A
breast development in females
6
Q
define menarche
A
menstrual cycles
7
Q
define spermarche
A
spermatogenesis
8
Q
define adrenarche
A
adrenal androgen production
starts approx two year before gonadarche
9
Q
define pubarche
A
pubic hair development
10
Q
what are the female secondary sexual characteristics?
A
- breast development
- hair growth (pubic, axillary)
- sweat gland composition (skin oiliness, acne)
- changes to external genitalia
11
Q
what are the male secondary sexual characteristics?
A
- deepening of voice
- hair growth (pubic then axillary + facial)
- sweat gland composition (skin oiliness, acne)
- changes to external genitalia
12
Q
which hormone causes the development of secondary sexual characteristics in males?
A
testosterone
13
Q
which hormone causes the development of secondary sexual characteristics in females?
A
oestradiol
14
Q
what age does puberty occur in girls?
A
onset = 8-13 years
15
Q
what age does puberty occur in boys?
A
onset = 9-14 years
16
Q
what is usually the first sign of puberty in girls?
A
thelarche (e.g. breast development)
17
Q
what is the expected testicular size in prepubertal boys?
A
< 4ml
18
Q
what is the expected testicular size in adult men?
A
> 15ml
19
Q
what is GnRH secretion like in childhood?
A
quiescence of HPG axis during childhood
i.e. inactivity, dormancy
20
Q
what is GnRH secretion like in puberty?
A
increased nocturnal GnRH pulsatility
21
Q
what is GnRH secretion like in adulthood?
A
normal pulsatile GnRH secretion
22
Q
what is ‘mini-puberty’ in in males?
A
when GnRH/LH/FSH/oestradiol/T increase in the foetus but falls during infancy to the quiescent phase of childhood
= testicular descent, penile length, Sertoli cell maturation, behavioural effects
(neonatal/foetal activation of the HPG axis)
23
Q
what is precocious puberty?
A
when puberty commences before the age of 8
more common in girls > boys
24
Q
what is delayed puberty?
A
when puberty commences after the age of 14
more common in boys > girls
25
when does menarche occur?
mean age = 12.7 years
(soon after peak height velocity)
approx 2 years after thelarche (breast development)
26
define primary amenorrhoea
absence of menses at age 15 years in the presence of normal growth and secondary sexual characteristics
27
define secondary amenorrhoea
when a woman who already menstruates does not get her period for at least 3-6 months
(but common for periods to be anovulatory/irregular for first 18 months)
28
what is the commonest physiological cause of secondary amenorrhoea in women?
pregnancy (!)
29
how long is the menstrual cycle on average?
approx 28 days
| can be 24-35 days, +/- 2 days each month
30
define amenorrhoea
1) absence of periods for at least 3-6 months
OR
2) up to 3 periods in total in a year
31
define oligomenorrhoea
irregular/infrequent periods
1) >35 day cycles
2) 4-9 cycles per year
32
differentiate between amenorrhoea and oligomenorrhoea
amenorrhoea = absence of periods
oligomenorrhoea = few periods
33
what happens in the follicular phase of the menstrual cycle?
1) increased FSH production
2) stimulates follicular development
3) FSH stimulates the inner granulosa cells of the follicles to start producing E2 and inhibin
4) via negative feedback from E2, FSH levels fall
5) restrict the FSH window and non-dominant follicles, with no FSH, undergo atresia
34
what does reduced FSH secretion in the follicular phase of the menstrual cycle cause?
negative feedback due to increased E2 production
= reduced FSH
= follicular atresia of the non-dominant follicles
35
what happens in the pre-ovulatory phase of the menstrual cycle?
1) the most E2 secretion happens from the dominant/Graafian follicle
2) the increase in E2 causes a switch to a positive feedback w the gonadotrophins
3) an LH surge results (and to a lesser extent, an FSH surge)
4) the LH surge causes ovulation
36
which hormone is secreted primarily in the luteal phase of the menstrual cycle?
progesterone
37
which blood test is done to see if ovulation has taken place?
midluteal D21 progesterone
38
which hormone dominates the proliferative phase of the uterine cycle?
oestradiol
39
which hormone dominates the secretory phase of the uterine cycle?
progesterone
40
what happens in the proliferative phase of he uterine cycle?
endometrial lining regrows
41
what happens in the secretory phase of he uterine cycle?
transformation of the endometrial lining to be receptive for implantation
42
what is the impact of continuous, non-pulsatile GnRH secretion?
decreased LH/FSH secretion
43
what is GnRH pulsatility like during the menstrual cycle?
follicular phase = 90-120 mins
luteal phase = 180-240 mins
44
define hypogonadism
in men = reduced testosterone
in women = reduced oestrogen
45
what is primary hypogonadism?
reduced/no sex steroid production due to damaged gonads
= low E2/T but high LH + FSH
46
what are the possible causes of hypogonadism in men?
infection, trauma or cancer of the testes
47
what is the commonest physiological cause of primary hypogonadism in women?
menopause
48
what is secondary hypogonadism?
reduced/no sex steroid production NOT due to damaged gonads BUT due to a secondary/pituitary cause
= low E2/T and low LH + FSH
49
what are some causes of secondary hypogonadism?
high prolactin
| pituitary tumour
50
what is secondary hypogonadism also called?
hypogonadotrophic hypogonadism
51
what hormone levels are expected in primary hypogonadism in women (e.g. menopause)?
low E2/T
high LH + FSH
low inhibin
52
why are inhibin levels low in menopausal women?
due to their follicular pool being very small, they have very little inhibin
(this + low E2 causes increased FSH)
53
what are the symptoms of menopause?
- skin dryness
- hair thinning
- hot flushes
- mood disturbance
- osteoporosis
- sexual dysfunction
- weight gain
- amenorrhoea
- cessation of fertility
- climateric periods
54
why is osteoporosis a symptom of menopause?
decreased bone mineral density
= as E2 is required to stimulate osteoblast activity
(so in menopause, with little/no E2, osteoblasts cannot function to stimulate bone formation)
55
what are perimenopausal women compared to postmenopausal women?
perimenopausal = within 1 year of the last menstrual period (LMP)
postemenopausal = after 1 year of the LMP
56
why is menopause said to be climateric?
irregular periods in years close to menopause
57
how is menopause treated?
hormone replacement therapy = oestrogen replacement
| must also add progeterone! if endometrium is intact
58
why are oestrogen and progesterone both given to treat menopause in women w an endometrium?
giving just oestrogen = stimulates the endometrium so MUST ADD PROGESTERONE to prevent the risk of endometrial hyperplasia/cancer
59
when do AMH levels peak in women?
in early adult life
60
what is the average age menopause occurs?
45-55 years
| very few = <1% undergo premature menopause before 40 years
61
what are the symptoms of early menopause?
same symptoms as early menopause
62
what is early menopause also known as?
premature ovarian insufficiency
| conception can still happen in 20% of the cases
63
how is early menopause diagnosed?
high FSH (>25 iU/L)
= x2 at least 4 weeks apart
64
what are the main causes of early menopause?
autoimmune
genetic (fragile X syndrome, Turner's syndrome)
cancer therapy
65
how is the total testosterone in circulation found?
60% = SHBG-bound testosterone (strongly bound = unavailable)
38% = albumin-bound (weakly bound = bioavailable)
2% = free testosterone (active)
66
what can testosterone in circulation bind to and how does each differ?
1) SHBG = strongly bound to this and so is unavailable
| 2) albumin = weakly bound to this so is bioavailable
67
in late-onset hypogonadism, why does free testosterone fall?
usually, SHBG increases w age and so more binds to the free testosterone
= reduces free testosterone levels bc SHBG-bound version is unavailable
68
when is the optimal time to measure testosterone?
1) highest in the morning, so should measure it before 11am
| 2) measure it fasting as presence of glucose can cause T levels to fall by 20%
69
why is testosterone best measured fasting?
as presence of glucose can cause testosterone levels to fall by 20%, affecting final results
70
what are the symptoms of testosterone deficiency?
- sexual dysfunction (low libido, erectile dysfunction)
- low energy levels
- mood disturbance
- increased fat + reduced muscle mass
- gynaecomastia
- reduced spermatogenesis
- reduced bone health
71
why do some males with low/borderline testosterone levels have normal sperm production?
(testosterone is required for spermatogenesis)
- testosterone is usually higher in the testes than elsewhere in the blood and so if there are low blood levels of T, the intratesticular levels are usually sufficient enough for spermatogenesis
72
which enzyme catalyses the conversion of testosterone into oestrogen?
aromatase
73
which enzyme catalyses the conversion of testosterone into dihydrotestosterone?
5-alpha-reductase
74
where is testosterone normally converted into oestrogen?
- ovaries = granulosa cells
- testes = Sertoli cells
- brain
- bone
- skin
- adrenal gland
- adipose tissue
75
where is testosterone normally converted into dihydrotestosterone?
testes (seminal vesicle, epididymis)
prostate
liver
76
why is DHT (dihydrotestosterone) produced?
more potent ligand for androgen receptor
77
which oestrogen is testosterone converted into?
17B-oestradiol
78
which oestrogen is androstenedione converted into?
oestrone
79
name an aromatase inhibitor and its use
anostrazole
| e.g. breast cancer
80
name a 5-alpha-reductase inhibitor and its use
finasteride
| e.g. prostate cacer
81
what stimulates aromatase action?
```
age
obesity
insulin
gonadotrophins
alcohol
```
82
differentiate between primary and secondary hypogonadism
primary = problem w the ovaries or testes
secondary = problem w the hypothalamus or pituitary gland
83
why is testosterone important to men?
hair growth, sexual function, muscle, voice
84
why is oestrogen important to women?
bone health, skin, hair, sexual function
85
why is progesterone important to women?
endometrial preparation for implantation
86
what is the male equivalent to POI?
POI = premature ovarian insufficiency i.e. menopause before 40
in men = late-onset hypogonadism
