Puberty

Question 1

What is puberty?

Answer 1

Puberty is the process of physical, hormonal, and psychological maturation during which a child becomes capable of reproduction, driven by activation of the hypothalamo–pituitary–gonadal axis.

Question 2

At what age does puberty typically begin?

Answer 2

Girls: 8–14 years (avg 10–11); Boys: 9–14 years (avg 11–12). Girls start earlier due to higher body fat and leptin levels.

Question 3

Which hormonal axis regulates puberty?

Answer 3

The hypothalamo–pituitary–gonadal (HPG) axis: GnRH from hypothalamus → LH and FSH from pituitary → sex steroids from gonads.

Question 4

What triggers the onset of puberty hormonally?

Answer 4

Reactivation of pulsatile GnRH secretion from the hypothalamus after childhood quiescence, stimulating LH and FSH release.

Question 5

What role does leptin play in puberty?

Answer 5

Leptin, produced by adipose tissue, signals sufficient energy stores and helps initiate GnRH pulsatility—explaining earlier puberty in girls with higher fat mass.

Question 6

What are the first physical signs of puberty in girls and boys?

Answer 6

Girls: breast budding (thelarche). Boys: testicular enlargement (≥4 mL volume).

Question 7

Which hormone is primarily responsible for male secondary sexual characteristics?

Answer 7

Testosterone—produced by Leydig cells under LH stimulation—causes penile growth, voice deepening, and muscle mass increase.

Question 8

What are the main effects of FSH in puberty?

Answer 8

In boys, it acts on Sertoli cells to support spermatogenesis. In girls, it stimulates follicular development and oestrogen secretion.

Question 9

What are Tanner stages used for?

Answer 9

To clinically assess sexual maturation based on development of breasts/genitalia and pubic hair (stages 1–5).

Question 10

At what Tanner stage does menarche usually occur?

Answer 10

Menarche occurs around Tanner stage 3–4, approximately two years after breast budding.

Question 11

When does the adolescent growth spurt occur?

Answer 11

Girls: peaks at ~12 years; Boys: peaks at ~14 years, due to growth hormone, IGF-1, and sex steroid synergy.

Question 12

Which hormone causes epiphyseal plate closure?

Answer 12

Oestrogen (in both sexes) induces epiphyseal closure, ending longitudinal bone growth.

Question 13

How do body composition changes differ between boys and girls during puberty?

Answer 13

Boys gain more lean muscle mass (~30 kg), girls gain more body fat (~18 kg), reflecting effects of testosterone and oestrogen respectively.

Question 14

Define precocious puberty.

Answer 14

Onset of secondary sexual characteristics before age 8 in girls or 9 in boys.

Question 15

Differentiate central from peripheral precocious puberty.

Answer 15

Central (GnRH-dependent): premature activation of HPG axis. Peripheral (GnRH-independent): sex steroid production from gonads, adrenals, or ectopic sources.

Question 16

List three causes of central precocious puberty.

Answer 16

Idiopathic (commonest), hypothalamic hamartoma, CNS lesions or trauma.

Question 17

List three causes of peripheral precocious puberty.

Answer 17

CAH, McCune–Albright syndrome, adrenal or gonadal tumours, or severe hypothyroidism (TSH cross-reactivity).

Question 18

How is central precocious puberty treated?

Answer 18

Long-acting GnRH agonists (e.g., leuprolide) suppress premature GnRH stimulation, halting further sexual maturation.

Question 19

Define delayed puberty.

Answer 19

Girls: no breast by 13 or no menarche by 16. Boys: no testicular enlargement by 14 years or no pubertal progression within 5 years.

Question 20

Most common cause of delayed puberty?

Answer 20

Constitutional delay of growth and puberty—usually familial and self-resolving with normal final height.

Question 21

How can bone age help differentiate causes of delayed puberty?

Answer 21

Delayed bone age → constitutional delay. Normal bone age → permanent hypogonadism.

Question 22

Which investigations are used in puberty disorders?

Answer 22

Serum LH, FSH, oestradiol/testosterone, thyroid function, bone age X-ray, and brain or pelvic imaging as indicated.

Question 23

List high-yield hormones involved in puberty and their roles.

Answer 23

GnRH – initiates; LH/FSH – stimulate gonads; GH/IGF-1 – drive growth; leptin – permits onset; oestrogen/testosterone – sexual maturation.

Question 24

What are consequences of untreated precocious puberty?

Answer 24

Short adult stature (due to early epiphyseal closure) and psychosocial stress.

Question 25

What are risks of delayed puberty?

Answer 25

Low bone density, psychosocial distress, and possible underlying chronic illness or endocrine disorder.