20. Physiology of Puberty

Question 1

puberty definition

Answer 1

stage of physical maturation in which an individual becomes physiologically capable of procreation

Question 2

physical changes in puberty

Answer 2

growth spurt
secondary sexual characteristics
menarche, spermatogenesis

Question 3

endocrine changes

Answer 3

HPG synchrony - established in foetal life
until puberty, neural mechanisms suppress GnRH release
at 6-9 years: nocturnal GnRH release leads to increased FSH and LH - ovaries and testes become sensitised
development of positive/negative feedback mechanism
ACTH stimulates adrenals: development of pubic and axillary hair

Question 4

testes

Answer 4

increase in volume = sign of puberty beginning
Sertoli cells produce sperm (FSH control)
Leydig cells produce testosterone (LH control)

Question 5

ovarian cycle - follicular phase

Answer 5

initially, oestrogen rises due to FSH

LH surge overs mid cycle: ovulation occurs

Question 6

ovarian cycle - luteal phase

Answer 6

negative feedback after ovulation
no further ovulation in same cycle
progesterone secreted by corpus luteum

Question 7

age of menarche

Answer 7

related to : general health, genetic factors, nutritional factors 
mean age = falling 
body weight and fat % important 
mean weight = 47.8kg 
athletes, anorexia: late onset

Question 8

adrenarche

Answer 8

adrenal androgens: responsible for axillary and pubic hair
ACTH stimulates zona reticularis - DHEAS and androstenedione
girls - starts at 6, adequate levels by 8
boys - starts at 8, adequate levels by 10

Question 9

chronological order of puberty in girls

Answer 9

growth spurt
breast development
pubic hair 
axillary hair 
menarche

Question 10

chronological order of puberty in boys

Answer 10

testicular volume 
penile length 
pubic hair 
growth spurt 
axillary/facial hair 
deep voice

Question 11

age at beginning of puberty

Answer 11

girls - 10.9 years

boys - 11.2 years

Question 12

disorders of puberty

Answer 12

early/precocious 
girls - under 8 
boys - under 9 
delayed 
girls/boys - over 14

Question 13

precocious puberty

Answer 13

early/premature puberty
presence of true pubertal features at young and inappropriate age
central/peripheral
normal variants: premature thelarche/adrenarche

Question 14

concerns raised by early onset

Answer 14

possible underlying sinister cause - in boys up to 80%
emotional and psycho-social upheaval at inappropriately young age
early cessation of growth: decreased adult height

Question 15

central precocious puberty

Answer 15

gonadotrophin dependent
treated with long-acting LH analogue therapy
sustained supra-physiological LHRH levels - ceases gonadotrophin release

stops further pubertal progression

Question 16

premature thelarche

Answer 16

isolated breast development

usually seen in children < 2-3 years

Question 17

premature adrenarche

Answer 17

isolated pubic hair development

caution: first sign of puberty in some

Question 18

pseudo-precocious puberty - girls

Answer 18

isosexual or feminising - MAS, ovarian/adrenal

heterosexual or masculinising - congenital adrenal hyperplasia, ovarian/adrenal

Question 19

pseudo-precocious puberty - boys

Answer 19

isosexual or masculinising - congenital adrenal hyperplasia, adrenal/Leydig cell tumour
heterosexual or feminising - adrenal

Question 20

delayed puberty

Answer 20

absence of true pubertal onset at appropriate age

no necessarily lack of periods in a girl

Question 21

concerns raised by delay

Answer 21

possible sinister underlying cause
fear puberty will never occur
emotional and psychosocial upset of immaturity +esop with short stature
long term: reduced bone mineralisation

Question 22

Klinefelter’s syndrome

Answer 22

1 in 1000 male infants 
47 XXY 
behavioural problems
androgen deficiency 
azoospermia/infertility 
microgenitalia
lifelong testosterone treatment

Question 23

Turner’s syndrome

Answer 23

1 in 2000 female births
short stature, streak gonads, primary amenorrhoea
coarctation of aorta, horse shoe kidneys
webbing of neck
treatments: exclude congenital anomalies, GH therapy, pubertal induction and ongoing HRT