Precocious puberty (early puberty)

• Precocious puberty is when puberty starts earlier than eight years of age in girls and nine years in boys.
• Most of the time there is no known cause of precocious puberty. In some case it can be the result of an underlying medical condition.
• Precocious puberty for which there is no underlying medical condition can be effectively treated with a monthly hormone injection.
• It is not always possible to prevent the onset of precocious puberty, but you can reduce your child's risk by encouraging them to maintain a healthy weight and by keeping them away from external sources of sex hormones.

What is precocious puberty?

Puberty is the time in a young person's life when their body undergoes physical changes as they become sexually mature. Puberty begins with a series of hormonal triggers that start in the brain and result in the stimulation of a girl's ovaries or boy's testes to produce more sex hormones. This prompts changes such as the growth of facial hair in boys and the development of breasts in girls.

In the US, the average age for the onset of puberty is around 10 years for girls and 12 years for boys. However, in precocious puberty, this onset occurs earlier - before eight years of age in girls and before nine years in boys.

Causes and risk factors

Precocious puberty is thought to be the result of a complex interaction between genetic, environmental and physical factors. The reason for puberty beginning early depends on the type of precocious puberty; in many cases it is not known.

Risk factors for precocious puberty include:

• Gender - it is more common in girls;
• Obesity - girls who are overweight are at greater risk;
• Various medical conditions (see below);
• Radiation therapy of the central nervous system, and;
• Exposure to sex hormones - external sources of estrogen and testosterone, such as some creams and ointments.

Types

Central precocious puberty

Most of the time there is no known cause of central precocious puberty - puberty starts early in children with no underlying medical condition. However, in very rare cases this type of precocious puberty can be caused by:

• A tumor in the brain or spinal cord;
• A rare genetic disease called McCune-Albright syndrome that affects the skin and bones and causes hormonal problems;
• A group of genetic disorders that cause congenital adrenal hyperplasia, in which the adrenal glands produce too many hormones, or;
• Hypothyroidism, in which the adrenal glands do not produce enough hormones.

Peripheral precocious puberty

In peripheral precocious puberty, estrogen and testosterone are produced without the central control from the brain that normally triggers them. Sometimes they can be produced due to problems with the ovaries, testicles, pituitary gland or adrenal glands. Such problems include:

• A tumor in the pituitary gland or adrenal glands causing secretion of estrogen or testosterone;
• External sources of estrogen or testosterone, such as some creams or ointments;
• McCune-Albright syndrome;
• Ovarian cysts or tumors in girls;
• A testicular tumor in boys, or;
• Gonadotropin-independent familial sexual precocity, a rare genetic disorder in boys.

Signs and symptoms

Signs and symptoms of precocious puberty include:

• Growth of breasts or occurrence of the first period in girls;
• A deepening voice, growth of facial hair, or enlarged penis and testicles in boys, and;
• Rapid growth, acne, pubic or underarm hair or an adult body odor in boys or girls.

Precocious puberty symptoms include acne and growth of facial hair. 

Methods for diagnosis

A doctor will diagnose precocious puberty by:

• Physical examination and taking a medical history;
• Blood tests that measure hormone levels, and;
• X-rays of the hand and wrist to determine if bones are growing too quickly.

GnRH test

In order to determine the type of precocious puberty, the gonadotropin-releasing hormone stimulation (GnRH) test is performed. GnRH is a hormone the brain releases that begins the chain reaction that triggers puberty.

A shot of GnRH is given to the child, and a blood sample is then taken to see if it causes an increase in levels of other hormones. If the child has peripheral precocious puberty, their other hormone levels will not rise.

Additional tests

If peripheral precocious puberty is suspected, additional tests to determine the cause can be performed, including:

• Additional blood tests, and;
• Ultrasound to check for ovarian cysts or tumors.

If central precocious puberty is suspected, then additional tests will include:

• Magnetic resonance imaging (MRI) of the brain to check for any abnormalities, and;
• Thyroid testing, to check the thyroid gland is working normally.

Types of treatment

Treatment of precocious puberty depends on its type and cause.

Central precocious puberty for which there is no underlying medical condition can be treated with GnRH analogue therapy: every month your child will be given an injection of a drug such as leuprolide, to suppress puberty until the normal age of onset.

If there is an underlying medical condition causing precocious puberty, then it will be treated separately; for example, by removing a tumor if it is causing precocious puberty by secreting hormones.

Potential complications

Complications of precocious puberty include:

• Emotional problems - children who undergo puberty earlier than their peers can be self-conscious, which may affect their self-esteem, and;
• Shorter height in the long term - although children with precocious puberty usually grow taller than their peers when young, they also tend to stop growing earlier than usual, so they often end up shorter as adults.

Prognosis

Treatment outcomes depend on the type of treatment and cause.

In most cases, hormone therapy is very successful at stopping puberty. Puberty will start again about 16 months after the injections are stopped.

Prevention

It is not always possible to prevent the onset of precocious puberty, but you can reduce your child's risk by encouraging them to maintain a healthy weight and by keeping them away from external sources of sex hormones (estrogen and testosterone), such as some prescription medications and dietary supplements.