Premature Sexual Development

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Notes by Harriet Wood
Premature Sexual Development
‘Development of secondary sexual characteristics before aged 8 years in
females and 9years in males’
Due to:
a) Precocious puberty – when accompanied by a growth spurt.
b) Premature breast development (thelarche).
c) Premature pubic hair development (adrenarche).
Puberty
‘The period when secondary sexual characteristics begins to develop
and the potential for sexual reproduction is reached’
Hypothalamic gonadotrophins releasing hormone (GnRH) pulse remains
dormant throughout early childhood.
From age of 8 gradual ↑ of pulses GnRH (most pulses occur during sleep).
Leading to LH and FSH secretion.
(Leptin may be responsible for kick starting puberty).
Females
○ LH stimulations onset of menstruation (must have a BMI of 47kg).
Males
○ LH stimulates release of testosterone from Leydig cells and onset
of spermatogenesis.
○ Dihydrotestosterone stimulates secondary sexual characteristics.
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Notes by Harriet Wood
Precocious Puberty
Categorised according to levels of pituitary-derived gonadotrophins (LH
and FSH):
Gonadotrophin-dependant
a.
‘True’ PP
b.
↑LH >↑FSH
c.
Caused by: premature activation of the hypothalamic-pituitarygonadal axis.
Gonadotrophin-independent:
a. ‘False’ PP
b. ↓FSH ↓LH
c. Caused by: excess sex steroids
Causes
Gonadotrophin-dependant
i. Idiopathic / familial.
ii. CNS abnormalities
Congenital anomalies e.g. hydrocephalus.
Acquired e.g. post-irradiation, infection, surgery.
Tumours e.g. microscopic haemartomas.
iii. Hypothyroidism.
Gonadotrophin-independent
i.
Adrenal disorders
Tumour.
Congenital.
Adrenal hyperplasia.
ii. Ovarian – Tumour (granulosa cell).
iii. Testicular – Tumour (Leydig cell).
iv. Exogenous sex steroids.
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Notes by Harriet Wood
PP in Females
Usually idiopathic of familial – Follows normal sequence of puberty.
Organic causes (rare) – Associated with:
Dissonance when the sequence of pubertal changes is abnormal
e.g. isolated pubic hair with virilisation of the genitalia.
Rapid onset.
Neurological S&S e.g. neurofibromatosis.
Investigations
Ultrasound of ovaries and uterus
In premature onset of puberty: multicystic ovaries and enlarging uterus.
PP in Males (uncommon)
Usually has an organic cause.
Examine testes for:
1. Bilateral enlargement – Suggesting gonadotrophin release, usually from
intracranial lesion.
2. Unilateral enlargement – Suggests gonadal tumour.
3. Small testes – Usually adrenal cause (tumour/ hyperplasia).
Investigations
Investigate for tumour – Cranial MRI scan.
Management (M&F)
Detect and treat any underlying pathology.
Address psychological/ behavioural difficulties.
Female:
If GD – GnRH analogues (do not always treat).
If GI – Identify source of excess steroids – Inhibit androgen or oestrogen
production or action e.g. with medroxyprogesterone acetate.
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Notes by Harriet Wood
Premature Breast Development (thelarche)
Usually affects females between 6mths and 2years.
Enlargement may be asymmetrical
Differs from PP:
Absence of axillary/ pubic hair development.
Absence of growth spurt.
Self-limiting.
Investigations not required.
Premature Adrenarche
‘Pubic hair development before 8years in females and 9years in males’
No other signs of sexual development.
Maybe be slight ↑ growth rate.
Usually self-limiting.
Investigations (to exclude PP):
d. Ultrasound of ovaries and uterus.
e. Bone age.
Delayed Puberty
‘Absence of pubertal development by 14years in females and 15years in
males’
More common in males – mostly due to constitutional delay.
Causes
1. Constitutional delay of growth and puberty
2. Hypergonadotrophic hypogonadism
(High gonadotrophin secretion – Indicating gonadal response is impaired)
Chromosomal abnormalities: – Females only.
Turner’s syndrome (45 XO)
Klinefelter’s syndrome (47 XXY).
Steroid hormone enzyme deficiencies.
Acquired gonadal damage:
Ovarian damage e.g. chemotherapy
Torsion of testis
Testicular damage e.g. chemotherapy, radiotherapy
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Notes by Harriet Wood
Autoimmune disorder
Post-surgery
Anorchia (absence of one/both testes)
e.g. foetal vascular accident – Males only.
3. Hypogonadotrophic hypogonadism
(Low gonadotrophin secretions – Failure of LH and FSH release)
Systemic disease:
○ CF
○ Organ failure
○ Excess physical training.
○ Crohn’s disease
○ Anorexia nervosa/ Starvation ○ Severe asthma
Hypothalamopituitary disorders:
Panhypopituitarism
Isolated gonadotrophin / GH deficiency
Intracranial tumours
Kallmann’s syndrome
Acquired hypothyroidism
Investigations
Males:
a) Pubertal staging – Esp. testicular volume.
b) Identification chronic systemic disorders.
Females:
a) Karyotype.
b) Measure thyroid and sex
steroid hormones.
Management
Identify any underlying pathology. Reassure puberty will occur.
To speed up:
Males – Oral oxandrolone (accelerate growth but not secondary sexual
characteristics) or Low-dose testosterone (accelerate growth and secondary
sexual characteristics).
Females – Oestradiol.
Important Note
These notes were written by Harriet Wood, as a medical student in 2009. They are presented in
good faith and every effort has been taken to ensure their accuracy. Nevertheless, medical practice
changes over time and it is always important to check the information with your clinical teachers
and with other reliable sources. Disclaimer: no responsibility can be taken by either the author or
publisher for any loss, damage or injury occasioned to any person acting or refraining from action
as a result of this information.
Please give feedback on this document and report any inaccuracies to:
[email protected]
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