TOG: Precocious puberty in girls Flashcards
what is the definition of precocious puberty in girls?
development of secondary sexual characteristics before the age of 8
what is the overall incidence of sexual precocity ?
what is the male to female ratio?
incidence= 1 in 5000-1 in 10 000
female:male= 10:1
at what age does puberty normally start, how long does it usually last for?
what is the lower end of normal range for onset of puberty?
starts around age 10, lasts 3-4 years.
Lower end of normal age of onset is 8 years
what is the usual stages of puberty?
Thelarche, adrenarche, growth spurt usually occurs with breast budding- peak height velocity reached mid puberty,
lastly menarche
what is the median age of menarche in british teenagers?
13yrs
what are the 3 areas into which premature sexual development is classified?
- central precocious puberty (true gonadotrophin dependent)
- Peripheral (pseudo-, gonadotrophin independent)
- isolated variants: precocious thelarche/pubarche/ menarche
what does central precocious puberty result from?
premature activation of HPG axis
what percentage of central precocious puberty is idiopathic?
74%
what are the underlying disorders that can lead to central precocious puberty?
- tumours- pituitary, glioma, cranio-pharyngioma
- congenital- hydrocephalus, myelomeningocoele
- acquired- irradiation, head trauma, encephalitis/ meningitis, chemo
- secondary to peripheral
what pelvic USS findings are inkeeping with progressive CPP?
uterine volume >2ml or length >34mm, pear shaped uterus, endometrial thickening
what is the gold standard test for diagnosing central precocious puberty, how does it work?
LHRH stimulation test:
measure FSH and LH after giving GnRH analogue:
in pre-pubertal & thelarche variant- FSH response exceeds LH response.
in pubertal- LH response exceeds FSH response.
what response do you see in the GnRH stimulation test if central precocious puberty?
the test shows a pubertal response ( ie LH response exceeds FSH response)
Levels >8 are diagnostic of CPP
What does bone scans and xrays show in central precocious puberty?
Advanced bone age by more than 2 yrs
what are the 4 main aims of treatment in central precocious puberty?
- halt / regress 2ndry sex characteristics
- prevent early menarche
- retard skeletal maturation and improve final height
- avoid psychosocial/ behavioural sequelae
what is the main treatment for central precocious puberty?
GnRH analogues
At what age does giving GnRH analogues, for central precocious puberty, give most benefit for improving final height?
GnRH analogue does not improve final height in girls beyond 8 yrs old.
Benefit is seen in girls age <6yrs with early-onset central Precocious puberty.
only modest improvement in girls btwn 6-8yrs
how is treatment response to GnRH analogues monitored? (for central precocious puberty)
growth, pubertal progression, bone age, LHRH stimulation test- at regular intervals
in precocious puberty, after treatment with GnRH analogues is stopped, when do pubertal changes start to recur?
pubertal changes start to come back within months, mean time to menarche of 16 months
what are the adverse effects of GnRH analogues? is adult bone mineral density affected?
headache, hot flushes, mood swings, injection site reactions.
Long term- links to PCOS.
adult BMD appears to NOT be affected by childhood GnRHa
what does peripheral precocious puberty result from?
secretion of sex steroids, independent of the hypothalamo-pituitary function
how is peripheral precocious puberty recognised?
What are the main clinical features?
disordered sequence of pubertal events.
Main features- rapid growth, advanced bone age, pubic/axillary hair, clitoromegaly
what are the ovarian causes of peripheral precocious puberty? How would these present
estrogen secreting tumour= granulosa cell. Presents with breast development, abdominal pain, PV bleeding.
androgen secreting tumour= sertoli-Leydig, arrhenoblastoma. Presents with progressive virilisation
what are the adrenal causes for peripheral precocious puberty? How can this be differentiated from ovarian causes, CLINICALLY?
CAH, adrenal tumours- cause premature sex development but NOT GONADARCHE therefore there is NO breast development
What is commonest form of classic Congential adrenal hyperplasia, how does it usually present?
commonest form is 21-hydroxylase deficiency. Presents in neonatal period- ambiguous genitalia, salt-losing crisis.
Milder forms- presents with virilisation in late childhood
What are the common presentations with adrenal tumours
tumours produce androgens and cortisol. therefore get precocious pseudo-puberty with clinical signs cushings
what is McCune-Albright syndrome? what are the clinical manifestations?
Genetic mutation of GNAS1 gene.
abnormal bone cysts, cafe au lait spots, peripheral precocious puberty.
premature menarche can be first clinical sign
What are the main causes of peripheral precocious puberty?
- hypothyroidism
- CAH
- adrenal/ovarian tumours
- McCune-ALbright sydrome
- Secondary Central precocious puberty- due to prolonged steroid exposure (McCune-Albright, CAH)
What does bone age show with peripheral precocious puberty?
advanced bone age. apart from hypothyroidism
what does the LHRH stimulation test show in peripheral precocious puberty?
relatively flat gonadotroophin response
what tests should be done if an adrenal cause is suspected forprecocious puberty?
17-hydroxyprogesterone- raised in classic CAH (21-hydroxylase deficiency)
DHEA, DHEAS- produced in the adrenals and is marker of androgen-producing adrenal tumours/ enzyme defects
why might urine steroid profile and ACTH test be useful in precocious puberty?
identifies adrenal steroid synthesis defect.
urinary 17-ketosteroid levels very high in girsl with adrenal tumours
why might prolactin be raised in peripheral precocious puberty?
McCune-Albright syndrome: from PRL -secreting pituitary tumours.
Chronic hypothyroidism
what abnormality is seen on bone scans with McCune-Albright Syndrome?
Polyostotic fibrous dysplasia
what is the main cause for isolated breast development?
benign. Self-limiting.
thought to be due to episodic ovarian cyst formation/ sensitivity of breast to normal circulating oestrogen
what percentage of girls with isolated precocious breast development go on to develop central precocious puberty
14%
what is the definition of isolated premature adrenarche/pubarche?
early appearance of pubic hair prior to 8 yrs old in girls with out any other pubertal signs
what is the most common cause of isolated premature adrenarche?
precocious secretion of androgens from zona reticularis of adrenal cortex
