T2 L20 Physiology of puberty Flashcards
what is the definition of puberty?
Stage of physical maturation where an individual becomes physiologically capable of pro-creation
What are the 3 general physical changes that occur during puberty?
Growth spurt
Secondary sex characteristics
Menarche / spermatogenesis
What are the 5 physical changes occurring during puberty for girls?
Growth spurt Breast growth Pubic hair Axillary hair Menstruation
When do girls experience a growth spurt?
8-14 years
6-10cm per year
2.5 year duration
When does thelarche occur?
8-13 years
When does pubic hair growth occur in girls?
9-13 years
When does menarche occur?
10-16 years
When does pulsatile nocturnal GnRH release start?
At 6-9 years
Occurs every 90-120 minutes
Describe the endocrine changes during puberty
Increased GnRH leads to increased FSH and LH
Ovaries / testes become sensitised to effects of FSH and LH
Final phase is development of positive / negative feedback mechanism
What can be used to check the adrenals are stimulated?
Urine steroid profile
What do the testes produce?
Games (sperm)
Androgens (testosterone)
What controls Sertoli cells?
FSH
What controls leydig cells?
LH
What produces androgens?
95% from testes
5% from adrenals
What are the 2 phases in the ovarian cycle?
Follicular phase
Luteal phase
What happens in the follicular phase of the ovarian cycle?
Initially E rises (FSH) with LH surge mid-cycle
Ovulation occurs
What happens in the luteal phase of the ovarian cycle?
Negative feedback after ovulation
No further ovulation in same cycle
What is the age of menarche related to?
General health
Genetic factors
Nutritional factors
What was the mean age of menarche in 1840?
16.5 years
What was the mean age of menarche in 1990?
12.8 years
Describe the link between body weight/fat and menarche
Mean weight at menarche is 47.8kg
16-24% of body weight is fat
Athletes and patients with anorexia often have a late onset
When does adrenarche occur in girls?
Starts at 6
Adequate levels by 8
When does adrenarche occur in boys?
Starts at 8
Adequate levels by 10
What is the chronological order of puberty in girls?
Growth spurt Breast development Pubic hair Axillary hair Menarche
What is the chronological order of puberty in boys?
Testicular volume Penile length Pubic hair Growth spurt Axillary / facial hair Deep voice
When is puberty considered early or precocious?
Below 8 years in girls
Below 9 years in boys
What is early or precocious puberty?
Presence of true pubertal features at young and inappropriate age
What is central or true precocious puberty dependent on?
Gonadotrophin dependent
What are the concerns in early or precocious puberty?
Possible underlying sinister cause
Emotional or psycho-social upheaval at inappropriately young age
Early cessation of growth leading to decreased final adult height
When is puberty considered to be delayed?
Above 14 years for girls or boys
What is delayed puberty?
Absence of true pubertal onset at an appropriate age
It isn’t necessarily a lack of periods
What are the concerns with delayed puberty?
Possible sinister underlying cause
Fear that puberty will never occur
Emotional and psychosocial upset of immaturity
Long term sequelae of reduced bone mineralisation
What is a hypothalamic hamartoma?
Non-neoplastic homogenous sessile mass
Iso-intense to brain parenchyma in region of tuber cinerium in hypothalamus
What is the treatment of central precocious puberty?
Long-acting LHRH analog therapy
- sustained supra-physiological LHRH levels
-paradoxical cessation of gonadotrophin release
-stops further pubertal progression
Pubertal progression will resumed when treatment is stopped at 10-12 years
How common is Klinefelter syndrome?
1 in 1000 male infants
What are the symptoms of Klinefelter syndrome?
Frontal baldness absent Poor beard growth Tendency to grow fewer chest hairs Narrow shoulders Breast development Wide hips Female-type pubic hair pattern Small testicular size Long legs Behavioural problems Androgen deficiency Azoospermia / infertility Micro genitalia
What is the treatment for Klinefelter syndrome?
Lifelong testosterone replacement therapy
How common is Turner syndrome?
1 in 2000 live female births
What is the triad for Turner syndrome?
Short stature
Streak gonads
Primary amenorrhoea
What are the dysmorphia features of Turner syndrome?
Webbing of neck
Cubitus valgus
What is the treatment for Turner syndrome?
Growth hormone therapy
Pubertal induction and ongoing hormone replacement therapy
Active monitoring to detect co-morbidities
Assisted conception
What is the treatment for gonadotrophin deficiency?
Lifelong testosterone replacement therapy
