3. Puberty and its disorders Flashcards
What is puberty?
Going from non-repro state to repro state
Males: testicular volume more than 4ml
Females: breast development
What is the order of puberty development?
Adrenarche, Pubarche, Gonadarche
In adrenarche, where are adrenal androgens secreted from?
Zona reticularis (not apparent in neonates- layer only comes up when adrenarche occurs)
What is released in adrenarche?
dehydro-epiandrosterone (DHEA)
dehydro-epiandrosterone sulphate (DHEAS)
At what age does DHEA/DHEAS peak?
gradual increase from 6-15, peaks from 20-25, declines after 25 (called adrenopause)
What happens in pubarche?
axillary and pubic hair
increase sebum production= acne
At what age in boys and girls is it precocious puberty?
Girls: before 8
Boys: before 9-10
When does Gonadarche start?
around 11 years of age (4-5 years after adrenarche)
what is gonadarche?
Reactivation of the HPG axis
When is the HPG axis first activated?
16th gestational week
pulsatile GnRH secretion continues until 1-2 weeks postnatally
then stops
reactivates at 11 years of age
What is the pattern of GnRH througout puberty?
prepuberty= low GnRH levels early/mid= nocturnal GnRH rise mid/late= pulsatile GnRH consistent
What percentage of body fat do you need to go to puberty?
17%-18%
What percentage of body fat do you need to maintain menstrual cycle?
22%
What can stop you going into puberty?
inactivating mutation in kisspeptin peptide or receptor
if activation mutation in kisspeptin receptor= PRECOCIOUS PUBERTY
What is consonance?
smooth ordered progression of changes in puberty
What is the order of puberty in females?
- breast budding
- pubic hair growth
- peak height spurt
- menarche (the first occurrence of menstruation)
- pubic hair reaches adult stage
- breast reaches adult stage
What is the order of puberty in males?
- testicular volume more than 4mm
- pubic hair growth
- peak height spurt
- genitalia reach adult stage
- pubic hair reaches adult stage
What scale can we use to measure puberty?
Tanner scale (stages 1 to 5) - stage 2 (early puberty) stage 4 (latepuberty)
What does the tanner scale measure?
breast development
distribution of pubic hair
genital development
What are the physical changes in puberty in females?
thelarche (breast enlarge)= sign of E2 activity
pubic/axillary hair
uterus enlargement
peak height growth at 12 yrs
hips widen
HPG axis reawaken= increase ovarian volume and follicular growth
menarche (first period)
What is the peak height velocity in girls?
9cm/year
When is fertility attained for females?
NOT AT PUBERTY- only at tanner stage 4
What are the physical changes in boys in puberty?
increase in external genitalia penis growth scrotum growth (and skin changes) reproduction tract matures larynx enlargement (bc of androgens)= voice deepen pubic/axillary hair peak height spurt- 14 years of age shoulders broaden
What is used to measure testicular volume?
prader orchidometer- looks like bead on string- beads are compared to testicles on palpation
When do males become fertile?
At the beginning of puberty
What is the growth spurt an interaction of? (of which hormones)
GH and Oestrogen
How does oestrogen act for growth spurt?
biphasic
- low oestrogen- linear bone growth and maturation
- high oestrogen epiphyseal bones fusion
When does the growth spurt occur?
During the reactivation of the HPG axis
What is a piloseabceuous unit?
unit of hair follicle with sebaceous glands
What is a sebaceous pilosebaceous units?
increased sebum= so can get acne = under the influence of androgens
What is vellus pilosebaceous units and what are the 2 types?
terminal PSU- moustache and beard hair
apo PSU-these go on to form axillary and pubic hair
What is central precocious puberty?
When puberty happens before 8 in girls and before 9 in boys but still in consonance (in correct order)
What are the 2 types of precocious puberties?
Gonadotropin dependent (central) or Gonadotropin independent
What is central/gonadotropin dependent precocious puberty?
excess GnRH secretion
Excess LH/FSH secretion (pituitary tumour)
What are examples of gonadotropin independent precocious puberty?
Testoxicosis
McCune Albright Syndrome
Sex steroid secreting tumour
Pseudo-precocious puberty
What is Testoxicosis?
LH mutation receptor increase androgen FSH receptor not activated early virilisation no spermatogenesis
What is McCune Albright syndrome?
adenylyl cyclase enzyme is activated
gonadotropin receptors are activated (bc LH/FSH are Gs)
cafe au lait skin pigment bc melanin 1 corticoreceptor is hyperactivated
fibrous dysplasia
What is pseudo-precocious puberty?
premature adrenarche and pubarche
pubic hair
can also have congenital adrenal hyperplasia
What is congenital adrenal hyperplasia?
21 hydroxylase problem it converts progestogens to mineralcorticoids and glucorticoids mutation=so no happen anymore so androgens accumulate virilisation of genitalia
What is pubertal delay?
no secondary characteristics by 13 in girls and 14 in boys
or no menarche (period) by 18 yrs old
What is hypogonadotropic hypogonadism?
low LH , FSH
Give an example of hypogonadotropic hypogonadism
Kallman’s syndrome, hypopituitary
What is kallman’s syndrome?
GnRH neurone migration regulated by KAL gene
KAL mutated
GnRH neurones now not function
So LOW LH,FSH
What is hypopituitarism?
god knows lol
What is hypergonadotropic hypogonadism?
High LH and FSH
problem at gonadal level
so no negative feedback to reduce LH, FSH
What do you get as a result of hypergonadotropic hypogonadism?
gonadal dysgenesis
low Sex steroid levels
What is kleinfelter’s syndrome?
extra X (XXY)= MALES
low oestrogen= long arms/legs
small testicular size
pubic hair female pattern
What is turner’s syndrome?
Lack of X chromosome (XO)= FEMALES
Streak ovaries- underdeveloped
short
webneck
Why can we not measure GnRH and what do we use instead to see how GnRH is being released?
can’t enter hypophyseal circulation
use LH to see GnRH secretions
When do people show reduced response to GnRH?
anorexia nervosa, intense physical exercise= less gonadotropin levels= periods stop (amenorrheoa)
Who reaches growth spurt earlier and by how many years?
girls by 2 years
How do we measure sexual development?
- Auxology =measure height, body proportions, weight and how they all come together
- pubertal staging - tanner scale or orchidometer
- DEXA scan= bone age
- LH, FSH and sex steroid measurements= tells if HPG axis has been re-awakened or there is an isolated increase in one of them.
- adrenal steroids if CAH is suspected or a tumour
- MRI of hypothalamic-pituitary area
What is constitutional delay?
type of pubertal delay= HPG axis not reactivated
How do you treat precocious sexual development?
- > Anti-androgens can be used for premature adrenarche
- > A 5a-reductase inhibitor for something like testotoxicosis to stop virilisation of external genitalia
- > Aromatase inhibitor to stop oestrodiol and oestrogen production
- > Use long-acting GnRH analogue in central precocious puberty to down-regulate HPG axis and stop pubertal processes from continuing
What are psychological changes in puberty?
Increasing need for independence
Increasing sexual awareness/interest
Development of sexual personality
What is Hypothalamic hamartoma?
Found in 33% of patients with central precocious puberty.
non-physiological secretion of GnRH.
mostly benign
