Precocious puberty

Definition

Sexual development before the age of eight in girls, and age 10 in boys.

Description

Not every child reaches puberty at the same time, but in most cases it's safe to predict that sexual development will begin at about age 11 in girls and 12 or 13 in boys. However, occasionally a child begins to develop sexually much earlier. Between four to eight times more common in girls than boys, precocious puberty occurs in one out of every 5,000 to 10,000 American children.

Precocious puberty often begins before age 8 in girls, triggering the development of breasts and hair under the arms and in the genital region. The onset of ovulation and menstruation also may occur. In boys, the condition triggers the development of a large penis and testicles, with spontaneous erections and the production of sperm. Hair grows on the face, under arms and in the pubic area, and acne may become a problem.

While the early onset of puberty may seem fairly benign, in fact it can cause problems when hormones trigger changes in the growth pattern, essentially halting growth before the child has reached normal adult height. Girls may never grow above 5 ft (152 cm) and boys often stop growing by about 5 ft 2 in (157 cm).

The abnormal growth patterns are not the only problem, however. Children with this condition look noticeably different than their peers, and may feel rejected by their friends and socially isolated. Adults may expect these children to act more maturely simply because they look so much older. As a result, many of these children--especially boys--are much more aggressive than others their own age, leading to behavior problems both at home and at school.

Causes & symptoms

Puberty begins when the brain secretes a hormone that triggers the pituitary gland to release gonadotropins, which in turn stimulate the ovaries or testes to produce sex hormones. These sex hormones (especially estrogen in girls and testosterone in boys) are what causes the onset of sexual maturity.

The hormonal changes of precious puberty are normal--it's just that the whole process begins a few years too soon. Especially in girls, there is not usually any underlying problem that causes the process to begin too soon. (However, some boys do inherit the condition; the responsible gene may be passed directly from father to son, or inherited indirectly from the maternal grandfather through the mother, who does not begin early puberty herself). This genetic condition in girls can be traced only in about 1% of cases.

In about 15% of cases, there is an underlying cause for the precious puberty, and it is important to search for these causes. The condition may result from a benign tumor in the part of the brain that releases hormones. Less commonly, it may be caused by other types of brain tumors, central nervous system disorders or adrenal gland problems.

Diagnosis

Physical exams can reveal the development of sexual characteristics in a young child. Bone x-rays can reveal bone age, and pelvic ultrasound may show an enlarged uterus and rule out ovarian or adrenal tumors. Blood tests can highlight higher-than-normal levels of hormones. MRI or CAT scans should be considered to rule out intracranial tumors.

Treatment

Treatment aims to halt or reverse sexual development so as to stop the accompanying rapid growth that will limit a child's height. There are two possible approaches: either treat the underlying condition (such as an ovarian or intracranial tumor) or change the hormonal balance to stop sexual development. It may not be possible to treat the underlying condition; for this reason, treatment is usually aimed at adjusting hormone levels.

There are several drugs which have been developed to do this:

• Histrelin (Supprelin)
• Nafarelin (Synarel)
• Synthetic gonadotropin-releasing hormone agonist
• Deslorelin
• Ethylamide
• Triptorelin
• Leuprolide.

Prognosis

Drug treatments can slow growth to 2-3 in (5-7.5 cm) a year, allowing these children to reach normal adult height, although the long-term effects aren't known.

Further Reading

For Your Information

Books

• Carlson, Karen J., Stephanie A. Eisenstat, and Terra Ziporyn The Harvard Guide to Women's Health. Cambridge, MA: Harvard University Press, 1996.
• Franck, Irene and David Brownstone The Parent's Desk Reference. New York: Prentice Hall, 1991.
• Ryan, Kenneth J., Ross S. Berkowitz, and Robert L. Barbieri Kistner's Gynecology, 6th ed. St. Louis: Mosby, 1997.

  Organizations

• National Institute of Child Health and Human Development. NIH Bldg. 31, Room 2A03, 31 Center Dr. MSC 2425, Bethesda, MD 20892-2425. "Facts about booklet on precocious puberty." (301) 496-3454. http://www.nih.gov/nichd/

Gale Encyclopedia of Medicine. Gale Research, 1999.