Puberty, usually occurring during adolescence, is when kids develop physically and emotionally into young men and women. Usually, this starts to happen no earlier than about 7 to 8 years of age for girls and 9 years of age for boys (the average age is about 10 for girls and 11 for boys).

But what if a younger child — for example, a 5-year-old girl — begins showing the signs of puberty? How would it affect her?

Precocious puberty — the onset of signs of puberty before age 7 or 8 in girls and age 9 in boys — can be physically and emotionally difficult for kids and can sometimes be the sign of an underlying health problem.

Signs of Precocious Puberty

In girls, the telltale signs of precocious puberty include any of the following before 7 or 8 years of age:

• breast development
• pubic or underarm hair development
• rapid height growth — a growth "spurt"
• onset of menstruation
• acne
• "mature" body odor

In boys, the signs of precocious puberty before 9 years of age include:

• enlargement of the testicles or penis
• pubic, underarm, or facial hair development
• rapid height growth — a growth "spurt"
• voice deepening
• acne
• "mature" body odor

Many kids who show some of the early signs of puberty have what's known as "partial" precocious puberty. Some girls, usually beginning between the ages of 6 months and 3 years, may show breast development that later disappears or may persist without other physical changes of puberty.

Similarly, some girls and boys may experience early growth of pubic and/or underarm hair that isn't associated with other changes in sexual development. Kids with "partial" precocious puberty may require evaluation to rule out "true" precocious puberty or other health problems, but they generally need no treatment and usually will show the other expected signs of puberty at the usual age.

How Precocious Puberty Affects Kids

When puberty ends, growth in height stops. Because their skeletons mature and bone growth stops at an earlier age than normal, kids with precocious puberty usually don't achieve their full adult height potential. Their early growth spurt may make them initially tall when compared with their peers, but they may stop growing too soon and end up at a shorter height than they would have otherwise.

Going through puberty early can also be difficult for a child emotionally and socially. For example, girls with precocious puberty may be confused or embarrassed about physical changes such as getting their periods or having enlarged breasts well before any of their peers. But the hardest part may be the teasing that kids with the condition — especially girls — may experience.

Even emotions and behavior may change in kids with precocious puberty. Girls can become moody and irritable. Boys can become more aggressive and also develop a sex drive inappropriate for their age.

Causes of Precocious Puberty

The onset of puberty is normally triggered by the hypothalamus (the area of the brain that helps control pituitary gland function). It signals the pituitary gland (a pea-sized gland near the base of the brain) to release hormones that stimulate the ovaries (in girls) or testicles (in boys) to make sex hormones.

Sometimes, precocious puberty stems from a structural problem in the brain (such as a tumor), brain injury due to head trauma, an infection (such as meningitis), or a problem in the ovaries or thyroid gland that triggers the onset of puberty ahead of schedule — but this usually isn't the case.

For the majority of girls, there's no underlying medical problem — they simply start puberty too early for no known reason.

In boys, the condition is less common, and more likely to be associated with an underlying medical problem than it is in girls. In about 5% of boys, precocious puberty is inherited. Starting puberty early can be passed to the son from the father or to the son from the maternal grandfather through the mother (who will not be affected by the disorder). But less than 1% of girls affected by precocious puberty have inherited the condition.

Diagnosing Precocious Puberty

Talk to your doctor if your child shows any signs of early sexual maturation before age 7 or 8 in girls or age 9 in boys, including breast development, rapid height growth, menstruation, acne, enlarged testicles or penis, or pubic or underarm hair.

The physical changes boys and girls go through during puberty are usually evident to a doctor during an exam. To confirm a diagnosis of precocious puberty, the doctor may order blood and urine tests to detect elevated levels of sex hormones. And X-rays of your child's wrist and hand can show whether the bones are maturing too rapidly.

Imaging and scanning tests such as CT scans, MRIs (magnetic resonance imaging), and ultrasound studies can help rule out specific causes of precocious puberty, such as a tumor in the brain, ovary, or testicle.

Treatment for Precocious Puberty

If your doctor suspects that your child has precocious puberty, he or she may refer you to a pediatric endocrinologist (a doctor who specializes in growth and hormonal disorders in children) for further evaluation and treatment.

Once it's diagnosed, the goal of treating precocious puberty is to halt or even reverse sexual development and stop the rapid growth and bone maturation that can eventually result in adult short stature.

Depending upon the cause, there are two possible approaches to treatment:

1. treating the underlying cause or disease, such as a tumor
2. lowering the high levels of sex hormones with medication to stop sexual development from progressing

In some cases, treatment of an underlying health problem can stop the precocious puberty from progressing. But in most cases, because there's no other disease triggering the condition, treatment usually consists of hormone therapy that stops sexual development.

The currently approved hormone treatment is with drugs called LHRH analogs — synthetic hormones that block the body's production of the sex hormones that are causing the early puberty. Dramatic results are usually seen within a year of starting treatment with an LHRH analog, which is generally safe and usually causes no side effects in kids.

In girls, breast size may decrease — or at least there will be no further development. In boys, the penis and testicles may shrink back to the size expected for their age. Growth in height will also slow down to a rate expected for kids before puberty. A child's behavior usually becomes more age appropriate as well.

Caring for Your Child

Give your child a simple, truthful explanation about what's happening. Explain that these changes are normal for older kids and teens, but that his or her body has started developing a little too early. Keep your child informed about treatment and what can be expected along the way.

Also be sure to watch for signs that teasing or other difficulties associated with precocious puberty may be affecting your child's emotional development. Common warning signs to discuss with your doctor include:

• poor grades
• problems at school
• loss of interest in daily activities
• depression

How you cope with the issue can also determine how successfully your child will cope. The goal is to prevent kids from dwelling on sexual development or developing a poor self-image or low self-esteem. To create a supportive environment, try not to focus your comments on appearance; instead, offer praise for achievements in school or sports and support your child's participation in other activities.

The important thing to remember is that kids with precocious puberty can be treated. Doctors can help them preserve their adult height potential as well as limit the emotional and social difficulties they may face from maturing early.

Reviewed by: Steven Dowshen, MD
Date reviewed: October 2012