Some children may experience puberty earlier or later than others for several different reasons. In some cases this could be a sign of an underlying condition and tests may be needed.

Early (precocious) puberty

An unusually early, or precocious, puberty would be diagnosed if symptoms of puberty – such as breast development, enlargement of the testes and growth of pubic hair – start before six to eight years of age in girls and nine years in boys.

Causes

The onset of puberty is usually triggered by the GPR54 gene, which sends signals to your brain and triggers a chain reaction and release of hormones in your body.

The early start of this chain reaction can be caused by:

• a problem in the brain (such as a tumour)
• brain injury due to head trauma
• an infection of the brain (such as meningitis)
• a problem in the ovaries or thyroid gland
• an inherited tendency (it may run in your family)

However, for most girls there is no known reason for starting puberty early. In boys, early puberty is less common and more likely to be associated with an underlying medical problem.

Treatment for early puberty

In order to diagnose the cause of early puberty, your GP may recommend a blood test to check for any problems with your hormones.

Ultrasound scans and magnetic resonance imaging (MRI) scans may also be used to check for tumours and the function of glands and organs.

Depending on the cause, there are two ways early puberty can be treated:

• treating the underlying cause, such as a tumour
• lowering the high levels of sex hormones with medication to stop sexual development progressing

Treatment with medication is usually only recommended if it is thought that going through an early puberty would cause you problems later in life, such as having weak bones, or growing up particularly short. If this is not the case, having an early puberty will not usually cause any health problems.

Delayed puberty

In girls, an unusually late puberty would be diagnosed if:

• there are no signs of breast development by 14 years of age
• there is no public hair by the age of 14
• five years have passed since the beginning of puberty and the breasts have not reached full adult development
• a girl has not had her first period by age 16

In boys, an unusually late puberty would be diagnosed if:

• there were no signs of testicular development by 14 years of the age
• there is no public hair by the age of 15
• five years have passed since the beginning of puberty but the penis and testicles have not yet reached full adult development

Causes

The onset of puberty is usually triggered by the GPR54 gene, which sends signals to your brain and triggers a chain reaction and release of hormones in your body.

The delayed onset of this chain reaction can be caused by:

• an inherited tendency (late puberty may run in your family)
• having a long-term illness, such as cystic fibrosis, diabetes, or kidney disease
• malnutrition, possibly from an eating disorder, or a chronic illness such as cystic fibrosis
• over-exercising, such as in the case of professional athletes and gymnasts
• polycystic ovaries (cysts on the ovaries)
• tumours, or other internal damage to your glands
• hormonal conditions, such as having an underactive thyroid gland
• a genetic condition that affects your sexual development, such as androgen insensitivity syndrome (a rare condition where a person is genetically male, but their body is insensitive to male sex hormones)

Treatment for late puberty

If there is no obvious cause for delayed puberty, such as a long-term illness, your GP may need to carry out some tests to diagnose the cause.

You will probably have blood tests to check for any problems with your hormones. Ultrasound and MRI scans may also be used to check for tumours and the function of glands and organs.

As with early puberty, treatments for late puberty will depend on the underlying cause. In most cases, treating the underlying causes should trigger puberty. In some cases, you may need to take medicines containing hormones to trigger the start of puberty.