Physiology of puberty

Question 1

What are the events in puberty?

Answer 1

1) Thelarche (Breast development)
2) Menarche (onset of menstruation)
3) Adrenarche (increased androgen levels)
4) Pubarche (axillary and pubic hair development)
5) Gonadarche (maturation of gonads)

Question 2

What is Tanner’s pubertal development?

Answer 2

– 5 different stages
Girls: breast (B1-5), pubic hair (Pu1-5), axillary hair (A1-5), menarche
Boys: testicular volume > 4 ml (Te), penis enlargement (G1-5), pubic hair (Pu1-5), axillary hair (A1-5), spermarche

Question 3

What is meant by precocious puberty?

Answer 3

Occurrence of puberty before its age, <8 for girls and <9 for boys

1) True precocious puberty, gonadotropin dependant early maturation of HPG axis
Causes:
Idiopathic, familial
Intracranial lesions
Gonadotropin secreting tumors

2) Pseudo precocious puberty, gonadotropin independent by excess secretion of sex hormones

• You can differentiate between them by measuring the basal LH levels and following GnRH administration, in true increases after GnRH, in GIPP it won’t and basal LH is low

Question 4

What are the criteria for pubertal delay?

Answer 4

No breast development by age 13 in a female
No menses by age 15 in a female
Testicular size < 2.5cm or 4mL or pubic hair is not present by age 14 in a male

1) Hypogonadotropic hypogonadism (gonadotropin deficiency “secondary”)
- Decreases GnRH = decrease LH and FSH
Defects in hypothalamus

2) Hypergonadotropic hypogonadism (primary) happens when there is excess production of gonadotropins. (It indicates a defect in the gonads)
The hypothalamus produces GnRH which stimulates the production of LH and FSH. However, due to a defect in the gonads, there is no production of sex hormones, delaying puberty