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BSMS203 Repro (Theme 2) > 20. Physiology of puberty > Flashcards

20. Physiology of puberty Flashcards

1
Q

Disorders and syndromes of puberty

A

Disorders of Puberty
Premature Puberty
Delayed Puberty

Syndromes
Klinefelter Syndrome
Turner Syndrome

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2
Q

Definition of puberty

A

Definition:
The stage of physical maturation in which an individual becomes physiologically capable of pro-creation (sexual reproduction)

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3
Q

Physical changes in puberty

A

Physical changes:

  • Growth spurt
  • Secondary sex characteristics
  • Menarche/spermatogenesis
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4
Q

Physical changes in girls

A

GROWTH SPURT 8 - 14 yrs
6 - 10 cm / yr peak
2.5 yrs duration

BREAST GROWTH 8 - 13 yrs ( 11 yrs )
(Thelarche) Usually the first sign

PUBIC HAIR 9 - 13 yrs
(Pubarche) 1st Pubertal Sign in 25%

AXILLARY HAIR 9.5 - 15 yrs
(Adrenarche) May follow menarche

MENSTRUATION 10 - 16 yrs ( 13 yrs )
(Menarche)

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5
Q

Signs of puberty in boys

A

In boys, first sign of puberty is testicular size - testicular volume of 4 is about start of puberty
Growth spurt later in boys than girls, can grow 12-14cm in a year.
Axillary or pubic hair is not true puberty until see testicular volume of 4ml or above.

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6
Q

Endocrine changes in puberty - prepuberty

A

H-P-G synchrony – established in fetal life
Until puberty – neural mechanisms suppress GnRH release
At 6-9 yrs – pulsatile nocturnal GnRH release

Mini-puberty in babies - HPG axis becomes synchronous, gets ready for later maturation
Need LHRH test

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7
Q

How does FSH and LH change in puberty and what are the conseuqences

A

Pulsatile GnRH release (nocturnal) every 90-120 min - 6 to 9 y
increase in GnRH leads to increase in FSH and increase in LH
Ovaries/testes become sensitized to the effects of FSH and LH
Final phase: development of positive/negative feedback mechanism

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8
Q

What results in hair growth at puberty?

A

ACTH stimulates the adrenals – Pubic & Axillary hair

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9
Q

What is the role of the testes?

A

Production of gametes (sperms)
Sertoli cells under FSH control
Production of androgens (Testosterone)
Leydig cells under LH control
95% from testes, 5% from adrenals
Testosterone in blood – converted to DHT in the target organs
Testosterone is converted to oestrogen which acts on the long bones resulting in bone growth

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10
Q

The ovarian cycle

A

Follicular phase
Initially E rises (FSH) with LH surge in mid cycle
Ovulation occurs

Luteal phase
Negative feedback after ovulation
No further ovulation in the same cycle

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11
Q

Age of menarche

A

Related to general health, genetic and nutritional factors
Mean age is falling at a rate of 4 months per decade
- Mean age in 1840 = 16.5 y; 1990 = 12.8 y
One in 8 girls now reaches menarche while at primary school
Body weight and % fat is also important
- Mean weight at menarche is 47.8kg
- 16-24% fat
- Athletes, patients with anorexia – late onset

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12
Q

What is adrenarche?

A

Adrenal androgens – responsible for axillary and pubic hair

ACTH stimulates zona reticularis of adrenal cortex

DHEAS & Androstenedione:
Girls – starts by 6, adequate levels by 8
Boys – starts by 8, adequate levels by 10

Test with urine steroid profile test

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13
Q

Chronological order of puberty in girls

A 
Growth spurt
Breast development
Pubic hair
Axillary hair
Menarche
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14
Q

Chronological order of puberty in boys

A 
Testicular volume
Penile length
Pubic hair
Growth spurt
Axillary / Facial hair
Deep voice
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15
Q

When is puberty considered early or precocious?

A

Girls – under 8 yrs

Boys – under 9 yrs

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16
Q

When is puberty considered delayed?

A

Girls – over 14 yrs
Boys – over 14 yrs

But if there is no breast budding at all by 13 then investigate for treatment because it means androgens aren’t working

17
Q

Precocious puberty

A

Early or Premature puberty
Presence of true pubertal features at an young & inappropriate age

Central or True precocious puberty
Gonadotrophin dependent
Peripheral or Pseudo-precocious puberty
Gonadotrophin independent

Normal variants
Premature Thelarche
Premature Adrenarche

18
Q

Central or true precocious puberty

A

Gonadotrophin dependent

19
Q

Peripheral or pseudo-precocious puberty

A

gonadotrophin independent

20
Q

Concerns raised by early onset

A

Possible underlying sinister cause
- Boys – upto 80%
Emotional & pyscho-social upheaval at an inappropriately young age
Early cessation of growth leading to decreased final adult height

21
Q

Central precocious puberty

A

Long acting LHRH analog therapy

  • Sustained supra-physiological LHRH levels
  • Paradoxical cessation of gonadotrophin release
  • Stops further pubertal progression

Pubertal progression resumes when treatment stopped (at 10-12 yrs)

22
Q

Normal variants

A

Premature thelarche
Isolated breast development
Usually seen in children <2-3 yrs of age

Premature adrenarche
Isolated pubic hair development
Caution: first sign of puberty in some
And . . .

23
Q

Pseudo-precocious puberty in males

A

Iso-sexual or masculinising
CAH, Adrenal/Leydig cell tumor

Hetero-sexual or feminising
Adrenal

24
Q

Pseudo-precocious puberty in females

A

Iso-sexual or feminising
MAS, Ovarian/Adrenal

Hetero-sexual or masculinising
CAH, Ovarian/Adrenal

25
Q

Delayed puberty

A

Absence of true pubertal onset at an appropriate age
Not necessarily lack of periods in a girl
X-files – very important

Normal variant
- Constitutional growth & pubertal delay

26
Q

Concerns raised by delay

A

Possible sinister underlying cause
Fear that puberty will never occur
Emotional and psychosocial upset of immaturity, specially when associated with short stature
Long term sequelae: Reduced bone mineralization

27
Q

Klinefelter syndrome

A 
1 in 1000 male infants
47 XXY / Multiple X
Behavioural problems
Androgen deficiency
Azoospermia / Infertility
(Micro genitalia  Sex change)
Lifelong testosterone replacement therapy
28
Q

Turner syndrome

A

1 in 2000 live female births
Triad - Short stature, streak gonads, primary amenorrhoea
Dysmorphic features – Webbing of neck, cubitus valgus
Coarctation of aorta, horse shoe kidneys
Early clue - Lymphedema

Surprisingly normal !!!

Turner Mosaic

29
Q

Managing turner syndrome

A 
Exclude co-existing congenital anomalies
Growth Hormone therapy
Pubertal induction + ongoing HRT
Active monitoring to detect co-morbidities
Assisted conception
30
Q

Normal variant of delayed puberty

A 
Constitutional delayed growth &amp; puberty
More common in boys
Small &amp; Short in school days
Late onset of puberty
Bone age delayed slightly

Family history – often present

Normal adult height
Pubertal induction – sometimes necessary

BSMS203 Repro (Theme 2) (26 decks)

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