Puberty
Endocrinology
Prepubertal stage: (<8yo) highly sensitive to negative feedback in the HPG axis to test/oestrogen therefore FH and sex hormone undetectable
Peripubertal period: before first clinical sign of puberty, nocturnal pulsatile (1.5-2hr) GnRH of increasing amplitude, thus FH detectable in sleep. Pulses spread to day in puberty.
Kisspeptin (acting on GPR54) and Glutamate stimulate GnRH
Preproenkephalin and GABA inhibit GnRH
Transforming growth factor β (TGF-β) also involved
NB Adrenache is variably define 1) as onset of detectable hormone change 2) 2 as part of the clinical progression ie meaning Pubarche/sweat/odour/acne
Positive feedback of oestrogen in mid-cycle causes increased LH
Variation in pattern but usually:
Biochem Adrenarche (6y) > Thelarche (10y) > Pubarche ie clinical adrenarche (11y) > Peak Ht Velocity (11.5y) > Menarche (12.5y)
Biochem Adrenarche (6y) > Gonadarche/scrotal thinning (11.5y) > Penile growth/Scrot Pigment > Pubarche ie clinical adrenarche > PHV (13.5)
Starts earlier in obesity (adipose cells produce oestrogen), later in anorexia/lean elite athletes e.g. gymnasts/ballet
Think circle around body 2 adrenals > 2 gonadarche (stimulates 2 thearche) > 1 long > multiple long (pubarche) > 1 liver (PHV) > reproductive (menarche/spermarche)
Failure of puberty
Hypogonadotrophic hypogonadism
Precocious puberty:
Central
Peripheral
CAH can have variable effect on puberty
Tall stature (caused by delayed epiphyseal fusion)
Aromatase (converts testosterone to oestrogen) deficiency
Oestrogen receptor defects
Prepubertal stage: (<8yo) highly sensitive to negative feedback in the HPG axis to test/oestrogen therefore FH and sex hormone undetectable
Peripubertal period: before first clinical sign of puberty, nocturnal pulsatile (1.5-2hr) GnRH of increasing amplitude, thus FH detectable in sleep. Pulses spread to day in puberty.
Kisspeptin (acting on GPR54) and Glutamate stimulate GnRH
Preproenkephalin and GABA inhibit GnRH
Transforming growth factor β (TGF-β) also involved
- Adrenache: activation of adrenal androgen secretion (DHEA-S >40um/dL)
NB Adrenache is variably define 1) as onset of detectable hormone change 2) 2 as part of the clinical progression ie meaning Pubarche/sweat/odour/acne
- Gonadarche: increase in testicle / ovary size (activation of HPG axis) stimulates
- Thelarche: breast tissue appearance
- Penile growth
- Pubarche: appearance of pubic hair
- Pubertal growth spurt (PHV)
- Menarche: onset of menses (Expect 6cm growth from here, irrespective of age of menarche)
- Spermarche: first production and nocturnal emission
Positive feedback of oestrogen in mid-cycle causes increased LH
Variation in pattern but usually:
Biochem Adrenarche (6y) > Thelarche (10y) > Pubarche ie clinical adrenarche (11y) > Peak Ht Velocity (11.5y) > Menarche (12.5y)
Biochem Adrenarche (6y) > Gonadarche/scrotal thinning (11.5y) > Penile growth/Scrot Pigment > Pubarche ie clinical adrenarche > PHV (13.5)
Starts earlier in obesity (adipose cells produce oestrogen), later in anorexia/lean elite athletes e.g. gymnasts/ballet
Think circle around body 2 adrenals > 2 gonadarche (stimulates 2 thearche) > 1 long > multiple long (pubarche) > 1 liver (PHV) > reproductive (menarche/spermarche)
Failure of puberty
Hypogonadotrophic hypogonadism
- GPR54 gene AR mutation
- Kallman Syndrome: X linked failure of puberty and anosmia (Failure of GnRH neurone migration to hypothalamus)
Precocious puberty:
Central
- Hypothalamic Hamartoma (w Gelastic seizures) ?related to TGF beta
Peripheral
CAH can have variable effect on puberty
Tall stature (caused by delayed epiphyseal fusion)
Aromatase (converts testosterone to oestrogen) deficiency
Oestrogen receptor defects