Precocious Puberty.

Precocious puberty (PP) has traditionally been defined as pubertal changes occurring before age 8 years in girls and 9 years in boys. A secular trend toward earlier puberty has now been confirmed by recent studies in both the United States and Europe. Factors associated with earlier puberty include obesity, endocrine-disrupting chemicals (EDC), and intrauterine growth restriction. In 1997, a study by Herman-Giddens et al found that breast development was present in 15% of African American girls and 5% of white girls at age 7 years, which led to new guidelines published by the LawsonWilkins Pediatric Endocrine Society (LWPES) proposing that breast development or pubic hair before age 7 years in white girls and age 6 years in African-American girls should be evaluated. More recently, Biro et al reported the onset of breast development at 8.8, 9.3, 9.7, and 9.7 years for African American, Hispanic, white non-Hispanic, and Asian study participants, respectively. The timing of menarche has not been shown to be advancing as quickly as other pubertal changes, with the average age between 12 and 12.5 years, similar to that reported in the 1970s. In boys, the Pediatric Research in Office Settings Network study recently found the mean age for onset of testicular enlargement, usually the first sign of gonadarche, is 10.14, 9.14, and 10.04 years in non-Hispanic white, African American, and Hispanic boys, respectively. For pubic hair, the mean ages were 11.47, 10.25, and 11.43 years, respectively, for non-Hispanic white, African American, and Hispanic boys. Lowering the age limit of PP in girls per LWPES guidelines has been estimated to misdiagnose 5% to 10% of girls with PP. Generally, girls with secondary sexual characteristics before 8 years should be monitored carefully. Normal puberty in girls most commonly begins with thelarche (the onset of breast buds), followed in a few months by pubarche (the onset of pubic hair), most often resulting from secretion of adrenal androgens (adrenarche). Gonadarche refers to sex hormone production from the ovary or testis. The differential diagnosis for PP (Table) includes central precocious puberty (CPP), peripheral precocious puberty (PPP), and normal variants such as premature thelarche (PT) and premature adrenarche (PA). CPP (gonadotropin-dependent) results from early activation of the hypothalamic-pituitary-gonadal axis and is much more common in girls and internationally adopted children. The increased risk for CPP in adopted children may reflect nutritional deprivation early in life, followed by increased adiposity after adoption. CPP is idiopathic in 90% of girls and is more likely to be associated with a pathologic cause in boys. Hypothalamic hamartomas (HH) are congenital, non-neoplastic tumors that include gonadotropin-releasing hormone (GnRH) neurons. HH are more common in boys and often present before 4 years of age. Kisspeptin and its receptor are involved in the neuroendocrine control of GnRH secretion, and recent mutations have been found to cause PP. AUTHOR DISCLOSURE Dr Long has disclosed no financial relationships relevant to this article. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.