Puberty

Question 1

Define puberty

Answer 1

Period during which adolescents reach sexual maturity + become capable of reproduction

Question 2

What causes puberty to begin?

Answer 2

• all reproductive hormones exist at birth, go into hiding around 4-6 months then reappear 10-12 yrs later
• KISS gene produces molecule which stimulates gonadotrophins initiate puberty
• activation of HPG axis

Question 3

Describe the HPG axis

Answer 3

FSH -> Testes -> Testosterone

LH -> Ovary -> Oestrogen + Progesterone

Question 4

What is the timing of puberty in girls?

Answer 4

• 8-14 yrs
• breast budding then pubic hair
• growth spurt onset with breast budding
• menarche at end

Question 5

What is the timing of puberty in boys?

Answer 5

• 9-15 yrs
• testicular + genital enlargement then pubic hair
• growth spurt mid-puberty

Question 6

How is bone age assessed?

Answer 6

X ray of non-dominant hand + wrist
Normal children may have bone delay up to 2 yrs
Cannot be used to make diagnosis

Question 7

What are the features of delayed puberty?

Answer 7

• small stature
• slow rate of growth in relation to age (low height velocity)
• delayed skeletal maturation (bone age)
• no evidence of sex-steroid production

Question 8

What is Hypogonadotrophic hypogonadism?

Answer 8

• delayed puberty from defect/not switching on hypothalamic/pituitary axis
• constitutional delay in growth + puberty (CDGP)
• hypopituitarism
• hypothyroidism
• chronic

Question 9

What is Hypergonadotrophic hypogonadism?

Answer 9

• delayed puberty with primary gonadal failure (from structural abnormalities in hypothalamic axis)
• gonadal dysgenesis =
• testicular + ovarian damage

Question 10

What is the differential diagnosis of delayed puberty?

Answer 10

Normal or low serum gonadotrophins =

• constitutional delay of growth + puberty
• hypothyroidism
• hypopituitarism

High serum gonadotropins =

• gonadal dysgenesis
• bilateral primary gonadal failure

Question 11

What is the treatment for delayed puberty?

Answer 11

• let nature take course or…
• give sex steroids (testosterone or oestrogen)
• used in patients with hypogonadotrophic and hypergonadotropic states
• treatment aimed at accelerating growth, inducing secondary sexual characteristics + boosting self-esteem

Question 12

Define precocious puberty

Answer 12

• Physical + hormonal puberty signs at earlier than normal age
• Onset of secondary sexual characteristics before 8 in girls, before 9 in boys
• Menarche before 9

Question 13

What are the features of precocious puberty?

Answer 13

• tall stature
• rapid growth rate
• advances skeletal maturation
• evidence of sex-steroid production: greasy skin + hair, acne, body odour, mood swings

Question 14

What are the types pf precocious puberty?

Answer 14

1. Independent
   - sex steroids secreted WITHOUT activation of HPG axis
   - sex steroids from adrenal or gonad
   - isolated breast development
   - virilisation = development of Mal characteristics in female or precociously in boys - excess androgen production
2. Dependent
   - early activation of HPG axis
   - majority idiopathic + girls
   - CNS disruption - tumours of HP region
   - post head injury/meningitis hydrocephalus
   - post cranial surgery or radiotherapy

Question 15

What is the UK protocol for investigation of precocious puberty?

Answer 15

• History
• Examination - pubertal staging
• Hormone measurements: testosterone/oestradiol, LH/FSH, adrenal androgens, TFT, GnRH test
• Radiology: bone age, pelvic US, MRI HP region
• DNA analysis for known genetic disorders

Question 16

What is the treatment for dependent precocious puberty?

Answer 16

• Let nature take course or…
• Switch off pituitary hormones (gonadotropins) which trigger puberty -> will sloe down/stop physical changes but will not reverse

Question 17

What is the outcome of GnRH therapy?

Answer 17

If treated before 8:

• 75% reach target height
• once treatment stopped, puberty continues
• long-term gonadal function unaffacted