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Sexual Precocity - Precocious Puberty

Overview, Causes, & Risk Factors

Puberty is a time when the body changes and is able to reproduce for the first time. Precocious puberty is a condition in which these changes occur earlier than normal.

What is going on in the body?

Hormones are released during puberty that foster physical growth and sexual development. The primary sexual changes that occur during puberty are the growth and maturation of the ovaries in girls and the growth and maturation of the testicles in boys. The secondary changes include the following:

  • the appearance of pubic and underarm hair, as well as facial hair in boys
  • increase in muscle mass and strength in boys
  • a rapid increase in height and weight
  • widening of the pelvis and breast development in girls
  • Precocious puberty occurs when the sexual hormones are released early. This is known as CPP, or central precocious puberty. With CPP, sexual changes occur in the normal order seen in puberty.

    PPP, or peripheral precocious puberty, occurs when other conditions trigger the early production and release of sexual hormones. With PPP, sexual changes may not occur in the normal order seen in puberty.

    Partial forms of precocious puberty are fairly common. Girls may develop breasts prematurely without other changes. Boys or girls may have sexual hair early, without other changes.

    What are the causes and risks of the condition?

    No underlying cause of precocious puberty can be found in 85% of girls and 40% of boys.

    For the remaining children, causes may include:

  • certain brain infections
  • cranial radiation, where the brain is exposed to X-rays
  • epilepsy, a central nervous system disorder causing seizures
  • fetal alcohol syndrome, which may occur if the mother drinks alcohol during her pregnancy
  • hydrocephalus, a condition in which there is extra spinal fluid in the brain
  • hypothyroidism, or an underactive thyroid gland
  • severe head injury
  • tumors of the ovaries, testicles, or other organs
  • structural defects or tumors in the brain
  • Precocious puberty can also be inherited. In a family where one parent carries the gene, there is a 50% percent chance that male infants would be affected. Female infants would have a 50% chance of being a carrier for the gene.

    Estrogen can cause premature sexual changes, like breast development, that can look like precocious puberty. These precocious changes go away after the estrogen exposure is stopped. Estrogens are found in the following:

  • certain meats, like poultry
  • cosmetics
  • hair and body creams
  • oral contraceptives
  • some vitamins

  • Symptoms & Signs

    What are the signs and symptoms of the condition?

    Puberty is called precocious in African American girls if they develop breasts before they are 5 or 6 years old. It is called precocious in Caucasian girls if they develop breasts before they are 6 or 7 years old. Precocious puberty is much more common in girls than it is in boys.

    African American and Caucasian boys both start puberty at about 9 years old. Puberty is called precocious for them if they begin sexual changes before this time.

    Children with CPP grow quicker than normal. Children with isolated, partial forms of precocious puberty, on the other hand, usually grow normally. In male CPP, the testicles enlarge before the penis begins to enlarge. In PPP, the penis grows much larger than the testicles.

    Mental development is usually the same as other children their age. Mood swings are not uncommon, but serious psychological problems are unusual.

    Other special conditions that may be seen include the following:

  • The early development of breast tissue without other signs of puberty, or premature thelarche. This occurs in the first 2 years of life, and lasts about 3 to 5 years. It rarely progresses any further. It is usually a benign condition, but it may be the first sign of true precocious puberty.
  • The appearance of sexual hair prior to age 8 in girls and age 9 in boys, or premature adrenarche. This occurs more often in girls, and in African American children. Rarely, it is caused by a disorder of the adrenal gland. The condition is usually benign. Girls who have this condition may develop polycystic ovarian disease as adults.
  • The early appearance of menstrual periods without other signs of puberty, or premature menarche. Usually girls who have this condition have only 1 to 3 early periods, then go on to have a normal puberty and menstrual cycle.

  • Diagnosis & Tests

    How is the condition diagnosed?

    Diagnosis of precocious puberty begins with a medical history and physical exam. The healthcare provider may order tests, including:

  • blood tests to check hormone levels
  • CT and MRI scans of body tissues
  • ultrasound
  • X-rays of the bones
  • Other tests may be ordered to verify suspected underlying disorders.

    Prevention & Expectations

    What can be done to prevent the condition?

    Precocious puberty cannot be prevented.

    What are the long-term effects of the condition?

    Some forms of precocious puberty cause the skeleton to mature quickly. At first, these children are taller than their peers. However, growth stops early for these children. Without treatment, they may end up being very short adults. Other long-term effects depend on the underlying conditions identified.

    What are the risks to others?

    Precocious puberty is not contagious and poses no risk to others.

    Treatment & Monitoring

    What are the treatments for the condition?

    Children with CPP may be treated if their bone age is 2 years more advanced than their chronological age. Injections of long-acting GnRH agonists, such as histrelin, can be given. These injections cause sexual development to stop. The normal growth rate returns. Girls can be given this treatment until they are between 11 and 12 years old. Boys can be given this treatment until they are between 12 and 13 years old.

    Children who have precocious puberty for reasons other than CPP need to have the primary disorder treated. This can include:

  • cortisol to treat adrenal gland disorders
  • removal of a tumor
  • thyroid hormone replacement for those with hypothyroidism
  • What are the side effects of the treatments?

    Some girls with CPP will have vaginal bleeding about 2 weeks after the first injection of a GnRH agonist. This bleeding usually does not recur.

    What happens after treatment for the condition?

    Because their growth and sexual development is advanced, some children with precocious puberty may feel isolated from their peer group. Frank and early discussion about their condition and body image may be reassuring. Parents and other concerned adults should be alert to signs that the child is having difficulty coping.

    How is the condition monitored?

    Any new or worsening symptoms should be reported to the healthcare provider.


    Author:John Wegmann, MD
    Date Written:
    Editor:Ballenberg, Sally, BS
    Edit Date:05/31/01
    Reviewer:Barbara Mallari, RN, BSN, PHN
    Date Reviewed:05/01/01