Physiology of Puberty

Question 1

Thelarche

Answer 1

Breast Growth
8-13 years
usually first sign

Question 2

Adrenarche

Answer 2

Axillary/pubery hair formation

-ACTH stimulates zona reticularis of adrenal cortex

Question 3

Causes of early adrenarche

Answer 3

• Ethnicity
• excessive androgen (e.g simple virilising CAH)
• Precocious puberty

Question 4

Timeline of female puberty

Answer 4

2-3 years approx.

1. Growth spurt
2. Thelarche
3. Pubic hair
4. Axillary hair
5. Menarche

Question 5

Mini puberty

Answer 5

H-P-G synchrony – established in fetal life

Until puberty – neural mechanisms suppress GnRH release

At 6-9 yrs – pulsatile nocturnal GnRH release

Question 6

What causes axillary and pubic hair?

Answer 6

ACTH increase stimulates adrenal glands

Question 7

Endocrine changes in puberty

Answer 7

Pulsatile GnRH release (nocturnal) every 90-120 min - 6 to 9 y

GnRH leads to increase FSH and LH

Ovaries/testes become sensitized to the effects of FSH and LH

Final phase: development of positive/negative feedback mechanism

Question 8

Testes development

Answer 8

Sperm production
FSH–Sertoli

Increased testosterone
-Leydig/Adrenals

Testosterone converted to DHT in target organs

Question 9

Timeline of puberty in boys

Answer 9

3-5 years

1. Testicular volume
2. Penile length
3. Pubic Hair
4. Growth Spurt
5. Adrenarche/Pubarche
6. Voice breaking

Question 10

Central or True precocious puberty

Answer 10

Gonadotrophin dependent
(Girls <8, Boys<9)

Girls

• mainly idiopathic
• hypothalamic hamartoma

Boys
-Mainly hypothalamic hamartoma

other causes

• brain trauma
• cerebral palsy

Question 11

Peripheral or Pseudo-precocious puberty

Answer 11

Gonadotrophin independent

-Early activation of the gonads/adrenals that activate the axis

E.g

• CAH
• Ovarian/Adrenal/Testicular tumour
• McCune-Albright

Question 12

Central Precocious puberty

-treatment

Answer 12

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)

Question 13

Klinefelter Syndrome

Answer 13

duplication of the X chromosome

LH and FSH is high

Question 14

Turner Syndrome

-Triad of features

Answer 14

-loss of one X chromosome
Short stature, streak gonads, primary amenorrhoea

can lead to premature ovarian failure

Question 15

3 causes of peripheral precocious puberty-

Answer 15

Congenital adrenal hyperplasia

McCune- Albright syndrome

Adrenal tumour

Ovarian/ Testicular tumour.