The Doctor's Office:

Puberty different for every child

By BRUCE A. EPSTEIN

© St. Petersburg Times, published March 29, 2001

Puberty is a complex series of events in the life of a young person. Considerable variation exists in the onset, duration and speed of sexual maturity in children.

In most cases, girls begin to develop breasts and then pubic hair between ages 8 and 13. Menstrual periods typically start at age 12 or 13. Boys normally develop testicular enlargement and then pubic hair between ages 9 and 14. Most girls are physically mature by about age 14 and boys two years later.

The onset of puberty is triggered by the pituitary gland, a pea-size structure at the base of the brain that is under the influence of the hypothalamus gland. Before puberty begins, higher brain functions prevent the hypothalamus from allowing the pituitary gland to begin secreting hormones. At the time of puberty, the pituitary gland begins secreting hormones called gonadotropins, which in turn stimulate the ovaries to produce estrogen or the testes to secrete testosterone.

These sex hormones are what normally cause sexual maturity to begin. The gonadotrophins also induce the development of eggs in the ovaries of girls and sperm in the testes of boys.

Puberty is considered to be delayed when physical changes do not appear by age 13 for girls and age 14 for boys. Though each child is different, the following are the most common symptoms of delayed puberty.

For girls:

Lack of breast development by age 13.

More than five years' lapse between breast growth and menstrual period.

Lack of pubic hair by age 14.

Failure to menstruate by age 16.

For boys:

Lack of testicular enlargement by age 14.

Lack of pubic hair by age 15.

More than five years to complete genital enlargement.

Fortunately, most children with delayed puberty are normal and just have a "constitutional delay" in their growth and development. This means that the delay in puberty is hereditary; often parents or close relatives also had a history of delayed puberty and a similar growth pattern. These youngsters usually also have a delayed maturation of their skeleton as well, so though they may be 14 years old, they may have the bone age (which can be revealed in an X-ray of the wrist and hand) of a 9- or 10-year-old.

Delayed puberty from heredity usually requires no treatment. Teens with constitutional delay will eventually begin puberty and then progress normally through its stages. Because they start later, these youngsters will continue to grow after most teens have stopped, "catching up" to their peers in height and sexual development.

Other children can have a medical condition that is causing the delay in beginning puberty because the ovaries or testicles are not secreting their sex hormones (estrogen or testosterone) appropriately. This can be caused by low thyroid function, eating disorders, malnutrition, poor diet, emotional deprivation, chromosomal abnormalities, primary testicular or ovarian failure, damage to the pituitary gland or other chronic medical conditions.

A child with delayed puberty should have a full evaluation by a pediatrician and will often need to see a pediatric endocrinologist, a specialist in hormone and growth disorders. The doctor evaluating the child is likely to do further testing, including blood tests to check hormone levels, an X-ray of the wrist to see if bone growth is normal, a CT or MRI scan of the head to look for brain injury and chromosome (gene) studies.

Treatment for delayed puberty depends on the cause of the problem. Often, after the underlying cause is treated, puberty proceeds normally. In some cases, treatment may involve hormone therapy to stimulate the development of secondary sexual characteristics or surgery to correct an anatomical problem.

It is important for parents to appreciate the psychological effects of beginning puberty late. These teens not only lack secondary sexual characteristics but are usually shorter than their friends. To an adolescent, looking like a small boy or girl and being different can be devastating, since the way teens see their own bodies has a lot to do with their self-esteem.

For example, a previously active teenage boy may stop participating in sports because he is uncomfortable undressing in front of his teammates. Adolescent girls may be embarrassed to babysit for children in the fourth and fifth grade because they are bigger than she is.

Parents can do several things. If the cause is constitutional delay, reassure your child that he or she is normal and will develop into a adult in his or her own time. Tell him that he is okay the way he is and that you love him that way. This will help him feel that someone understands. If the tests show a problem, tell your child that you will help her with any problems.

-- Bruce A. Epstein practiced pediatrics in St. Petersburg for 26 years. He edits the Web site http://www.kidsgrowth.com.

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