When puberty comes early
Puberty marks the end of childhood. But why does it sometimes start early? Puberty is considered precocious in girls younger than eight and boys younger than ten.
© Jupiter
And it seems that precocious puberty is becoming increasingly common. But why has the biological clock started to speed up? Do we know the causes?
Everyone recognises the signs of puberty, namely the appearance of secondary sexual characteristics: breast augmentation, appearance of pubic hair and menstruation in girls; increase in size of penis and testicles for boys. These changes generally begin between the ages of nine and ten for girls and at around 12, for boys. In all cases, puberty lasts about six years.
There are several factors that can influence the timing of puberty and whether it starts early or late: genetic factors, lifestyle, food intake and diet, levels of physical activity and weight (particularly body fat).
Three types of precocious puberty
There can be significant age differences between individuals at the onset of puberty. Some youngsters can experience precocious or early puberty; for others, it can be delayed. Early puberty is relatively rare and accounts for 1 to 2% of all medical consultations and 99% of cases concern girls.
There are three major types of precocious puberty: true precocious puberty: pseudo precocious puberty and dissociated precocious puberty.
True precocious puberty
True precocious puberty is caused by an early activation of the neurological and hormonal mechanisms that are responsible for sexual functions. Puberty is initiated in the brain: neurons in the hypothalamus produce secretions that lead to gonad growth and maturation. The gonads (sexual glands: in women these are the ovaries and in men, the testicles) produce sex hormones that stimulate the development of secondary sexual characteristics and the processes of spermatogenesis and ovagenesis. True precocious puberty usually begins between the ages of three and five. In this case, the body behaves as if the child were considerably older; the luteinizing hormone (LH) and the folliclestimulating hormone (FSH) reach adult levels several years too early.
True precocious puberty can be hereditary but it can also be caused by brain lesions: tumours, skin or bone defects, inflammatory sequelae, infantile hypothyroidism etc. Hypothalamic tumours are the most common cause of true precocious puberty in boys. However, for nine out of ten girls and two out of five boys, the cause of true precious puberty is unknown.
Pseudo-precocious puberty
Peripheral or pseudo precocious puberty is a lot less common, but can be easily diagnosed by a synacthen test. Precocious puberty may either be isosexual (development of sex-appropriate sexual characteristics) or heterosexual (development of opposite-sex sexual characteristics). Unlike true precocious puberty, the sex glands actually remain immature; the problem usually caused by a congenital adrenal hyperplasia or androgen- or oestrogen-producing tumours.
Dissociated precocious puberty
Disassociated or incomplete precocious puberty is associated with the isolated manifestations of pubertal development (also called precocious pubescence).
Premature thelarche is defined as premature breast development; premature pubarche or adrenarche is the premature appearance of pubic hair and premature menarche is precocious menstruation. These changes are often caused by a minor and transient malfunctioning of the hypothalamic-pituitary-gonadal axis. Nonetheless, early menstruation needs to be taken very seriously as there is often a serious underlying cause.
Early puberty linked to lifestyle
In recent years there has been an increase in the number of cases of precocious puberty. Most of the hypotheses put forward to explain this phenomenon blame our current lifestyle.
- Calorie intake and obesity (over the last twenty years, childhood obesity has doubled in the USA) could be responsible for the increasing number of cases of precocious puberty. Fat facilitates the production of oestrogen and insulin, two hormones that influence sexual development.
- Lack of exercise can similarly affect physical maturity. We know, for example, that intensive sporting activity can delay the onset of puberty.
- Some scientists believe that the presence of oestrogens and phthalates - chemicals used in the manufacturing of plastic - in cosmetics and beauty products may also be responsible.
- Exposure to environmental contaminants with oestrogenic activity (containing oestrogen-like chemicals) could also be linked to early puberty in girls.
However, there's no real cause for concern. Most cases of precocious puberty can be treated once the primary trigger has been removed. First of all, you need to identify the exact cause. You can do this through a series of examinations, for example X ray, CT scan, Nuclear MRI (NMRI). Then you need to try to re-set the body clock. And, go to see your doctor if you notice any signs of early puberty.
Copyright © 2010 Doctissimo
Posted 30.06.2010
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