Precocious puberty is the appearance of signs of pubertal development at an abnormally early age. In girls this has traditionally been considered to be before 8 years, and in boys before age 9. Normal puberty may vary with ethnicity, and whether the definitions should also vary has been a matter for debate.
Causes
Precocious puberty can be classified as follows.
Gonadotrophin-dependent precocious puberty (central precocious puberty (CPP))
This is also known as true precocious puberty. Premature activation of the hypothalamic-pituitary-gonadal (HPG) axis occurs. Most children (especially girls) suspected of having CPP do not have any specific abnormality but lie at one end of the normal distribution curve.
Idiopathic (sporadic or familial). No cause is found in 80% of girls and 40% of boys.Abnormalities of the central nervous system (CNS) include:Tumours, including gliomas, astrocytomas, hamartomas, pineal tumours and hCG-secreting germ cell tumours.CNS trauma or injury (causes include infection, radiation, surgery).Hamartomas of the hypothalamus.Congenital disorders such as hydrocephalus and arachnoid cysts.
Gonadotrophin-independent precocious puberty (or precocious pseudopuberty)
This accounts for about 20% of cases of precocious puberty and some of the specific causes are rare. The appearance of secondary sexual characteristics is due to the increased production of female or male hormones, which occurs independently of the maturation of the HPG axis. Causes include:
Congenital adrenal hyperplasia (CAH).Tumours: HCG-secreting tumours in the liver (hepatomas, hepatoblastomas), choriocarcinomas (of gonads, pineal gland, mediastinum, etc) and adrenal tumours (rare). Ovarian tumours may cause either masculinisation or feminisation. Testicular Leydig-cell tumours may cause early virilisation in males.McCune-Albright syndrome (MAS). A genetic condition in which affected individuals are at risk of multiple endocrinopathies, including thyrotoxicosis, Cushing’s syndrome, acromegaly, hyperparathyroidism, etc. Signs include typical café-au-lait spots on the skin, pathological fractures due to fibrous dysplasia of the bones, and recurrent ovarian cysts.Silver-Russell syndrome.Testotoxicosis (or familial male precocious puberty). An autosomal dominant condition characterised by progressive pubertal changes, rapid physical growth, skeletal maturation and sexually aggressive behaviour in the first 2-3 years of life.Severe hypothyroidism or van Wyk-Grumbach syndrome. Growth is arrested (unusual with precocious puberty) rather than accelerated.Exogenous oestrogen or androgen exposure (therapeutic or accidental.)
Benign variants of precocious pubertal development
Non-progressive precocious puberty. Following early signs of puberty, the situation stabilises or regresses rather than progressing.Isolated precocious thelarche. Early breast development without other features. Breast development may occur in girls aged 3 years and can then spontaneously regress. This is often seen in girls under the age of 3 years and is caused by maternal oestrogens in the early months. There is fairly static breast development before true puberty eventually occurs at the normal time. It is a benign condition confirmed by:Absence of any other signs of puberty.Normal growth with appropriate bone age (ie no growth spurt).Minimal increase in breast tissue with time (can even decrease).Appropriate uterine dimensions for age (ultrasound) with normal endometrial echo and no vaginal bleeding.Isolated precocious pubarche. Early pubic hair development (with or without axillary hair) without other features of puberty. Pubic hair may present both in boys and in girls aged <7 years, due to adrenal androgen secretion in middle childhood.Isolated precocious menarche. Isolated early vaginal bleeding in the absence of other causes or features.
Management
For cases of CPP with no underlying brain pathology and no psychosocial complications, treatment for the pubertal changes alone may not be required. Puberty can be arrested and growth hormone given if the height prognosis is poor. Examples of treatment include:
Surgery: tumours may require resection but resection of central lesions will not cause regression of the pubertal changes. Gonadal tumours require surgery with or without subsequent radiotherapy/chemotherapy.
Medical treatments include:
GnRH agonists are used in CPP, as well as for other aetiologies, including MAS and testotoxicosis. These come in a number of depot preparations. They work by overstimulating the pituitary, causing desensitisation and thereby less release of LH and FSH. They are continued until the time for normal puberty arrives. If started early they can help the individual achieve predicted adult height.
Glucocorticoids are used for CAH.
Testolactone is an aromatase inhibitor (therefore inhibits steroid biosynthesis). It is used most commonly for MAS but also in testotoxicosis. Other aromatase inhibitors such as letrozole and anastrozole have also been used in small case studies for MAS.
Tamoxifen has been used in MAS.
Ketoconazole may be used (for example, in testotoxicosis) to inhibit steroid biosynthesis.
Cyproterone acetate may be used for anti-androgen action. Flutamide is also used to counter androgen excess.
Medroxyprogesterone (a progesterone analogue) has also been used.
Complications
Psychological difficulties, including feeling stressed and becoming withdrawn because of the early physical changes. Poor self-esteem and bullying may be issues.
Behavioural problems and emotional problems.Early puberty accelerates growth but bone maturation is also accelerated and so adult height is reduced.
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