Puberty Flashcards
Define puberty
physiological, morphological and behavioural changes as the gonads switch from infantile to adult forms
Describe the process of puberty
inhibition of puberty diminishes
increased FSH and LH secretion
initiation of sex steroid secretion
sexual maturation
adolescent growth spurt
What factors influence timing of puberty?
genetic - strong correlation between parents and children/siblings
nutrition - obese children enter puberty earlier, 17% body fat needed for menses, 22% for ovulation
environment - earlier puberty in urban areas, closer to equator, lower altitudes
Requirements for puberty
normal capacity for growth
adequate nutrients
normal body composition
emotional wellbeing
good physical health
Secondary sexual characteristics in girls
ovarian oestrogens regulate the growth of breast and female genitalia
ovarian and adrenal androgens control pubic and axillary hair
Secondary sexual characteristics in boys
testicular androgens:
- external genitalia and pubic hair growth
- enlargement of larynx and laryngeal muscles –> voice deepening
What staging is used to classify puberty?
Tanner staging
What stages of puberty are the tanner stages roughly relating to?
pre-puberty = Tanner stage 1
early puberty = Tanner stage 2-3
later puberty = Tanner stage 4-5
What signifies the start of puberty in boys and girls?
boys = testicular volume 4mls
girls = breast stage 2
Order of male puberty
testicular enlargement and pubic hair occur first
growth of penis and growth in height starts after about 12 months
Order of female puberty
growth rate increases from onset of puberty
breast and pubic hair development is congruent
menarche occurs late and growth stops shortly thereafter
What is done in an endocrine evaluation of puberty?
clinical evaluation
pubertal staging
FSH, LH, testosterone, oestradiol, prolactin, thyroid function, karyotype, androstenedione, DHEAS
GnRH test
bone age xray (dominant hand + wrist)
pelvic ultrasound (girls)
What ages suggest precocious puberty?
girls <8y
boys <9y
How is early puberty classified?
central or gonadotrophin-dependent:
- usually girls
- usually idiopathic
- CNS lesion may be present
gonadotrophin-independent:
- sex-steroid production independent of FSH/LH
Name some puberty variants
premature thelarche
premature pubarche (adrenarche)
isolated premature menarche
adolescent gynaecomastia
Describe premature thelarche
isolated breast development - typically very young girls (1-4y)
non-progressive with no growth spurt
remits spontaneously
Describe premature pubarche
isolated pubic hair development
usually girls 5-7y
Describe isolated premature menarche
early onset of periods
despite no or minimal pubertal development
exclude hypothyroidism
Describe adolescent gynaecomastia
common in early to mid puberty in boys, particularly if obese
When is central precocious puberty always pathological?
in boys
- suggests CNS lesion
Causes of true (central) precocious puberty (GnRH dependent)
idiopathic precocious puberty
CNS tumours - optic glioma, hypothalamic astrocytoma
CNS disorders - developmental abnormalities, hypothalamic hamartoma, encephalitis, brain abscess, hydrocephalus, myelomeningocele, arachnoid cyst, vascular lesion, cranial irradiation
secondary central precocious puberty
psychosocial eg. adoption from abroad
Causes of precocious pseudo-puberty (GnRH-independent)
increased androgen secretion - congenital adrenal hyperplasia, virilising neoplasm, leydig cell adenoma, familial male precocious puberty (testotoxicosis)
gonadotrophin secreting tumours
mccune-albright syndrome
ovarian cyst
oestrogen-secreting neoplasm
(hypothyroidism)
Describe McCune-Albright syndrome
triad of:
- precocious puberty
- large irregular cafe au lait patches
- polyostotic fibrous dysplasia
mosaic expression of G-protein coupled receptor over-activity
spontaneous secretion of various hormones may occur
Describe congenital adrenal hyperplasia
inborn error of cortisol and/or aldosterone synthesis
mostly 21 alpha hydroxylase deficiency
large amounts of adrenal androgens and testosterone secreted, producing virilisation but with small testes
may go unrecognised in boyd
treatment with hydrocortisone replacement
Central precocious puberty treatment
GnRH analogues
non-pulsatile stimulation of FSH and LH secretion results in down regulation of responsiveness to GnRH
Gonadotrophin-independent precocious puberty
treatment of the underlying cause where possible
anti-androgen/androgen receptor blockers/aromatase inhibitors
What ages are classed as delayed puberty?
> 13y girls
14y boys
Causes of delayed puberty
constitutional delay in growth and adolescence
illness/malnutrition
failure of hypothalamus/pituitary (hypogonadotrophic hypogonadism)
gonadal failure
Describe constitutional delay
often familial
more common in males
associated short stature
spontaneous puberty will occur
relative disproportion
reduced final height
What illnesses can cause delayed puberty?
chronic disease:
- cystic fibrosis
- crohn’s disease
- juvenile arthritis
- steroid therapy
hypothalamic amenorrhoea:
- anorexia nervosa
- athletes/gymnasts
- leptin deficiency
What is Kallmann’s syndrome?
hypothalamic GnRH deficiency with anosmia
Name some causes of hypogonadotrophic hypogonadism
Kallmann’s syndrome
Prader-Willi syndrome
Pituitary gonadotrophin deficiency
Name some causes of gonadal failure
Klinefelter’s syndrome
Turner’s syndrome
Normal LH level pre-puberty
<0.3
Klinefelter’s syndrome karyotype
47XXY
Klinefelter’s syndrome features
mild developmental delay/autistic features
small, hard testes
gynaecomastia
elevated FSH, LH, low testosterone
Constitutional delay treatment
sex steroid replacement until puberty well-established
