Precocious puberty in girls (Pubertas Praecox)

In girls, puberty usually starts between the age of 8 and 13 years. The first sign is progressive development of breast tissue. If the ovaries produce sufficient female hormones to initiate breast development before the age of 8 years, this is considered as precocious pubertal development.

Precocious puberty occurs 10 to 20 times more frequent in girls than in boys. Compared with data from 40 years ago, puberty in girls starts 1 year earlier and more girls develop breasts before the age of 8 years. Specialists suspect a link with increasing weight in children. Fat tissue can produce low quantities of female hormones. Another hypothesis suspects the presence of environmental chemicals, mimicking the effect of female hormones.

In most cases, the normal puberty mechanism is activated too early (central pubertas praecox). In less than 5% of the girls with precocious puberty, the production of female hormones started in the ovaries without a signal from the brain (peripheral pubertal praecox)

The causes of precocious puberty often remain unknown. Some congenital conditions or tumours in the brain increase the chances of developing an early puberty. In some families, children develop an early puberty, indicating that a genetic factor is playing a role. Precocious puberty is also more frequent in children who were adopted internationally.

A peripheral precocious puberty can be caused by genetic changes due to chronic activation of the gonads (f.e. Mc Cune-Albright syndrome) or by tumours producing female hormones (granulosa cell tumours, germ cell tumours). Another cause is the accidental intake of female hormones (f.e. medication from  older sisters or mother)

• Essential for the diagnosis is the presence of breast tissue (stage B2 or further, see text on pubertal development in girls) before the age of 8 years. It is not always easy to differentiate between breast tissue and fat tissue in girls who are overweight. Breast tissue feels firmer and lies directly behind the nipple. Often, the nipple point protrudes and changes in colour.
• Female hormones make the mucosa from the labia thicker, causing a lighter colour.
• Often, but not always, some pubic hair appears in the genital region (P2 or more) and in the armpit.
• The sweat glands become active and can produce ‘adult’ sweat smell. The skin and hair become oilier due to the stimulation of the sebaceous glands.
• Female hormones stimulate the production of growth hormone, causing girls to grow faster. This can be visualised by putting all growth data on a growth curve.

The high levels of female hormones at a young age closes the growth plates and results in short stature.

Girls with precocious puberty often feel different than other children and sometimes they are being bullied at school. They have more psychological problems and show more risk behaviour at a young age. Some studies show associations between early puberty and other conditions, like diabetes, and cardiovascular diseases in adults.

The goal of the treatment is to synchronize the physical and psychological development with the chronological age and avoid short stature by early closing of the growth plates.

The type of treatment depends on the cause of the precocious puberty:

• Central precocious puberty

In most cases, the origin is a central precocious puberty with the hypothalamus producing high peaks of LHRH. For this form, medication (LHRH analogues) can block the LHRH from interacting with the pituitary gland. The currently available LHRH analogues need to be injected in the muscle or subcutaneously, and different forms with different duration of action exist. Some formulas only work for a few hours, but fortunately the pharmaceutical industry succeeded in binding these molecules to a gel permitting very slow release of the active substance during 1, 3 or even 6 months.

Usually, the treatment is very effective. The breast development stops, and a small reduction of the breast volume is often obtained. The emotional fluctuations and ‘puberty behaviour’ also decrease. The closure of the growth plates is delayed, with a positive effect on adult height, especially in girls with puberty onset before the age of 6 years. In older girls, the effect on adult height is variable.

The most common adverse events of the treatment are pain, redness and swelling at the injection site, exceptionally, an allergic reaction to the medication can occur. After the first injection, 5-10% of the girls experience a vaginal bleeding that does not reoccur with continuation of the treatment. After stopping the treatment, puberty development continues and most girls have menstruations within 2 years

During the treatment, the bone density may decrease, but this will restore after stopping the treatment.

• Peripheral precocious puberty

The peripheral precocious puberty can be treated with medication reducing the production of female hormones in the ovaries or in some tumours and/or blocking the effect of female hormones. If a tumour causes the production of female hormones, this can be surgically removed.