Physiology of puberty

Question 1

What are the endocrine changes that occur during puberty?

Answer 1

HPG synchrony – established in fetal life.
Until puberty – neural mechanisms suppress GnRH release.
At 6-9 yrs – pulsatile nocturnal GnRH release. increased GnRH leads to increased FSH and LH. ovaries / testes become sensitised to effects of FSH and LH.
Final phase: development of positive/negative feedback mechanism.
ACTH stimulates adrenals – pubic and axillary hair.

Question 2

What is the role of the testes during puberty?

Answer 2

Production of sperms. sertoli cells under FSH control.
Production of testosterone. leydig cells under LH control.
Testosterone in blood – converted to DHT in target organs

Question 3

What occurs during the follicular phase of the ovarian cycle?

Answer 3

Initially E rises (FSH) with LH surge in mid cycle.

Ovulation occurs.

Question 4

What occurs during the luteal phase of the ovarian cycle?

Answer 4

Negative feedback after ovulation.

No further ovulation in same cycle.

Question 5

What is adrenarche?

Answer 5

Adrenal androgens – responsible for axillary and pubic hair.
ACTH stimulates zona reticularis of adrenal cortex.
DHEAS and androstenedione - starts by 6 in girls and 8 in boys.

Question 6

What is the chronological order of puberty in girls?

Answer 6

Growth spurt, breast development, pubic hair, axillary hair,

menarche

Question 7

What is the chronological order of puberty in boys?

Answer 7

Testicular volume, penile length, pubic hair, growth spurt,

axillary / facial hair, deep voice

Question 8

At what age is the beginning of puberty in boys and girls?

Answer 8

Girls: 10.9 years
Boys: 11.2 years

Question 9

When is puberty considered to be precocious or delayed?

Answer 9

Precocious: girls – under 8. boys – under 9 yrs.
Delayed: girls – over 14. boys – over 14 yrs.
Arbitrary / conventional cut off points.

Question 10

What are the types of precocious puberty and what are they dependent on?

Answer 10

Central or true precocious puberty - gonadotrophin dependent.
Peripheral or pseudo-precocious puberty - gonadotrophin independent.

Question 11

Which condition can cause precocious puberty?

Answer 11

Hypothalamic hamartoma

Question 12

What is the treatment for central precocious puberty?

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.

Question 13

What is premature thelarche?

Answer 13

Isolated breast development, usually seen in children <2-3 yrs of age

Question 14

What is premature adrenarche?

Answer 14

Isolated pubic hair development, caution: first sign of puberty in some. must eliminate cancer.

Question 15

What is the treatment for Klinefelter syndrome?

Answer 15

Lifelong testosterone replacement therapy

Question 16

What is the treatment for Turner’s syndrome?

Answer 16

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