Paediatrics: Precocious puberty

Precocious puberty

This is defined as the early onset and rapid progression of puberty. Age criteria vary. In White European children, precocious puberty (PP) is defined as <8yrs in females and <9yrs in males.

Classification and causes

·  is either central or peripheral in origin. The various causes of PP are as follows.

Central (true) PP (gonadotrophin-dependent)

·  Idiopathic (familial/non-familial).

·  Intracranial tumours: e.g. hypothalamic hamartoma, craniopharyngioma, astrocytoma, optic glioma.

·  Other CNS lesions: hydrocephalus, arachnoid cysts, traumatic brain injury, cranial irradiation.

·  Secondary central PP: early maturation of the hypothalamic–pituitary– gonadal axis due to long-term sex steroid exposure, e.g. congenital adrenal hyperplasia (CAH), McCune–Albright syndrome.

Puberty occurs as a consequence of early physiological (true) activation of the hypothalamic–pituitary–gonadal axis (central). A normal sequence of pubertal development is observed.

Central PP may also be idiopathic and familial. Girls with central PP are more likely to have idiopathic central PP, whereas in boys there is a much greater risk of intracranial tumours.

Peripheral PP (gonadotrophin-independent)

·  Gonadal: McCune–Albright syndrome; ovarian tumours (e.g. benign cyst; granulosa cell tumour); testicular tumour; familial testitoxicosis (LH receptor-activating mutation).

·  Adrenal: CAH; adrenal tumour (carcinoma; adenoma).

·  Human chorionic gonadotrophin (HCG)-secreting tumours: e.g. CNS (chorioepithelioma; dysgerminoma).

·  Iatrogenic (exogenous sex-steroid administration).

Puberty is due to mechanisms that do not involve physiological gonado-trophin secretion from the pituitary. The source of sex steroid may be endogenous (gonadal or extragonadal) or exogenous. Endogenous hor-mone production is independent of hypothalamic–pituitary–gonadal activ-ity. An abnormal sequence of pubertal development is usually observed.

Assessment

History

A detailed history should be obtained:

·Age when first signs of pubertal development observed.

·Which features of puberty are present and in what order did they appear?

·Evidence of growth acceleration.

·Family history: careful enquiry about the age of onset of puberty (including age of menarche in females) within other family members.

Examination

·Puberty (Tanner) staging.

·Measure height; weight; head circumference.

·Review previous growth records if available.

·Measure parents’ heights and calculate MPH/family height target.

·Skin lesions: e.g. café-au-lait marks (McCune–Albright; NF-1).

·Abdominal/testicular masses.

·Neurological examination: visual fields; fundoscopy.

Investigations

Baseline screening tests should be considered.

·Plasma LH and FSH levels.

·Plasma sex hormone: oestrogen/testosterone.

·Other serum androgen levels: e.g. 17-OH progesterone, DHEAS, androstendione.

In addition, undertake the following:

·Urine: steroid profile (sex/adrenal steroids).

·BA X-ray.

·Pelvic US (ovarian morphology; testicular masses).

·Abdominal US, e.g. adrenal glands.

·MRI scan brain.

GnRH (LHRH) test: measurement of basal and post-GnRH LH, and FSH levels as indicator of hypothalamic–pituitary function.