Precocious puberty

Precocious puberty

Puberty is a period of maturation which occurs during adolescence, involving the development of reproductive glands, external genitalia as well as secondary sex characteristics.

Onset of puberty:

• Girls - 11
• Boys - 13

These values are averages, however, and the age of onset may vary considerably.

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Definition: Precocious puberty is defined as the onset of puberty before the age of 8 in girls, and 9 in boys.

Types:

• Central (gonadotropin-dependant) - due to elevated GnRH
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• Peripheral (gonadotropin-independent) - due to overproduction of sex hormones by the gonads. GnRH levels may be normal or low.

Central

Aetiology

• Idiopathic in most cases
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• GnRH releasing tumour in the hypothalamus
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• Radiation exposure - impairs sensitivity of hypothalamus and pituitary to the negative feedback effect of sex hormones.
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• Obesity - increased insulin and leptin levels are linked with early development of sex characteristics.

Peripheral

Androgen production - ↑

• Ovarian cyst - most common cause overall
• Leydig cell tumour
• Congenital adrenal hyperplasia

Oestrogen production - ↑

• HCG-secreting germ cell tumour
• Oestrogen secreting tumour of the adrenal gland

Genetic conditions

• McCune-Albright syndrome

Other

Hypothyroidism - increased TSH levels linked with precocious puberty

Clinical features

Early development of primary and secondary sexual characteristics.

Boys

Primary:

• Growth of penis and testicles
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• Sperm being produced
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• Secretions from prostate gland

Secondary:

• Formation of pubic, armpit and facial hair
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• Deepening of voice

Girls

Primary:

• Menarche - onset of menstrual bleeding
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• Uterus and vagina grow

Secondary:

• Thelarche - onset of breast development
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• Body changes - hips widen and waist narrows
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• Pubic and armpit hair form

Boys and girls

• Accelerated growth
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• Early skeletal maturity

Investigations

1st line - serum gonadotropin (LH and FSH) levels.

• Central - ↑, perform GnRH stimulation test: if LH and FSH increase, then diagnosis is confirmed. CT/MRI the brain to look for an underlying cause.
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• Peripheral - ↓, see below.

Imaging - perform an ultrasound of the testicles, pelvis and abdomen.

Further bloods - TSH, T3/T4, β-HCG, 21β-hydroxylase

Management

Central

The underlying cause must ultimately be addressed, however:

GnRH agonist i.e. goserelin can be used. It binds to the GnRH receptors on the pituitary gland, initially causing LH and FSH production to increase, however the receptors then become desensitised to GnRH and as a release gonadotropin release decreases.

Peripheral

Treatment for peripheral precocious puberty depends on the underlying cause.

• Ovarian cyst - most cysts regress spontaneously, so a “watch and wait” approach is preferred.
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• Hormone secreting tumour - surgical excision.
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• Congenital adrenal hyperplasia - see learning card on CAH.