Puberty - Adolescent Health

Puberty

·        Physiology:

o  Pre-puberty: Inhibition of GnRH pulse generator by higher centres 

o  Puberty: increasing frequency and amplitude of pulsitile GnRH secretion, initially at night, with FSH (® follicles or Sertoli cells) and LH (® hormone production) secretion in response 

o  Also involvement of adrenal glands ® androgens ® secondary sex characteristics (eg pubic hair but not ­testicular size) 

·        Terminology:

o  Gonadarche: onset of gonadal function

o  Thelarche: onset of breast development

o  Adrenarche /Pubarche: Onset of development of sexual (pubic/axillary) hair

o  Menarche: Onset of menstruation

o  Spermarche: Onset of production spermatozoa

·        Clinical signs:

o  Measured in Tanner stages (1 = no development, 5 = adult)

o  Girls: breast development first (ovaries enlarge first but can‟t see them)

o  Boys: Testicular enlargement (use orchidometer) 

o  Pubic hair development initially related to adrenal androgens and may be discordant with other changes 

·        What‟s normal: 

o  Girls: traditionally < 8 years or > 13 years abnormal. But ­ number of girls have breast development at 7. Menarche relatively unchanged at 12 (ie earlier onset, but endpoint relatively unchanged). Getting earlier by 3-4 months per decade (but psycho-social development unchanged) 

o  Boys: < 9 or > 14 abnormal.  No strong evidence of it getting younger

Normal variants

·        Mini-puberty in neonatal period

o  Usually neonate – but up to 4 months

o  Due to hormones in utero and underdeveloped CNS inhibitory mechanisms

o  Breast development +/- milk (Witches milk - completely normal)

o  Withdrawal uterine bleeding (following endometrial development in utero)

o  Estrogenic effects on genitalia

·        Premature Thelarche

o  Isolated early breast development

o  Tanner 2 or 3 maximum

o  No advancement in bone age

o  Follow-up to ensure it is isolated not progressive (ie that it‟s a normal variant)

·        Premature Adrenarche:

o   Isolated early pubic hair development +/- acne +/ BO

o   Caused by adrenal androgens

o   No advancement in bone age and normal menarche/spermarche

o   Need follow-up (eg to exclude adrenal tumour)

o   ?Association with future hyperandrogenism (eg Polycystic Ovary Syndrome)

·        Gynaecomastia:

o   Breast development up to stage 3 during male puberty (75% of males)

o   Usually in early puberty – resolves in about 2 years

o   Reassurance, occasionally surgery

o   Pathological:

§  In rare instances: Klinefelter‟s syndrome, gonadal failure

§  Outside of puberty (eg oestrogen producing tumour)

·        Key sign indicating normal: normal bone age/no growth spurt

Precocious Puberty

·        Definition arbitrary

·        Consequences:

o   Short stature

o   Psychosocial (out of sync with peers)

·        Clinical signs: Old bone age and growth spurt (in addition to eg breast development)

·        Gonadotrophin Dependent: 

o   = Central/complete.  Hypothalamic or pituitary cause and ® balanced development

o   Girls:

§  Normal progression through puberty (ie variant of normal?)

§  Rapid progression suggests pathology

o   Boys:

§  Normal progression of puberty

§  Less common than girls, more likely to be pathology

o   Causes:

§  Idiopathic (95% in girls)

§  Hypothalamic hamartoma: developmental anomaly

§  Tumours (eg of hypothalamus or pituitary)

§  Other CNS conditions (eg hydrocephalus, spina bifida)

·        Gonadotrophin Independent:

o   = Peripheral/Incomplete.  Peripheral cause and not all characteristics of normal puberty

o   Girls: rapid progression or viralisation

o   Boys: Testes remain small, rapid progression

o   Causes:

§  Hormone ingestion

§  Congenital Adrenal Hyperplasia (ie adrenal androgens)

§  Tumours: adrenal, gonadal or hCG secreting

§  Autonomous hormone production (rare)

·        Investigations:

o   Bone age from hand x-ray

o   Measure hormones

o   GnRH stimulation test

o   Imaging

·        Treatment: 

o   GnRH agonist for central precocious puberty via depot. If GnRH is not pulsitile it switches off FSH and LH

o   Girls: progesterone delays menarche

Delayed Puberty

·        Hypogonadotropic: Hypothalamic/pituitary causes:

o   Constitutional delay (check for bone age)

o   Exercise/nutrition (eg anorexia)

o   Generalised pituitary failure (eg post surgery/radiotherapy for CNS tumour)

o   Rare isolated deficiencies

·        Hypergonadotrophic: Gonadal failure

o  Chromosomal: eg XO, XXY

o  Infections (eg mumps, especially during puberty)

o  Autoimmune

o  Surgery, radiotherapy, chemotherapy

o  Galactosaemia

·        Other:

o  Structural (eg normal puberty but no menarche)

o  Intersex disorders: chromosomal sex <> phenotypic sex

·        Pubertal arrest: always pathological (eg pituitary tumour)

·        Investigation and treatment:

o  Gonadotrophins +/- GnRH stimulation test

o  Hormone replacement

o  Fertility issues (eg with gonadal failure)