Sex hormones (18) Flashcards
How do we define puberty?
- maturation of reproductive organs
- production of sex-steroids
- develop 2y sexual characteristics
- attain capability to reproduce
What is Tanner Staging/how is it used to describe development?
Thelarche= breast development in girls (1= pre pubertal…5= adult breasts)
Testicular volume in boys (1.5ml prepubertal…adult size testes >15mls)- assessed using orchidometer
Pubarche= pubic hair onset in both (1=prepubertal…5= adult hair)
What is gonadarche?
activation of gonads by HPG axis
What is menarche?
onset of menstrual cycles
What is spermarche?
onset of sperm production
What is adrenarche?
onset of androgen production by adrenal glands
What 2y sexual characteristics are caused by estradiol in girls?
- breast development
- hair growth: pubic and axillary
- sweat gland changes: oily skin/ acne
- changes to external genitalia
What 2y sexual characteristics are caused by testosterone in boys?
- deepening of voice
- hair growth: pubic then axillary, facial
- sweat gland changes: oily skin/acne
- changes to external genitalia
What age is the onset of puberty for girls?
8-13
What age is the onset of puberty for boys?
9-14
What is the difference in the stage at which peak height is obtained for girls/boys?
in girls: at around tanner stage 2-3
in boys: 3-4
What are hormonal changes like during puberty?
adrenarche: DHEA (adrenal androgen) gradually increase
gonadarche: LH + FSH inc.
testosterone inc. in boys
oestradiol inc. in girls
What is GnRH and how can we describe its secretion?
gonadotrophin releasing hormone
- pulsatile secretion
Why are LH and FSH called gonadotrophins?
they stimulate the gonads (testes/ovaries) to make testosterone/oestrogen
How does GnRH secretion vary with age?
- in late foetal life and early neonatal life: activation of HPG axis (“mini puberty”)- important for early maturation of gonads
- in childhood: quiescence (inactivity) of HPG axis
- as puberty is approached: inc. nocturnal GnRH pulsatility
- as puberty is established: normal pulsatile GnRH secretion
How do we classify delayed puberty?
doesn’t start by 14yrs
more common in boys
How do we classify precocious puberty?
starts before 8yrs
more common in girls