Early pubertal development is referred to as sexual precocity or precocious puberty. Central precocious puberty is a term reserved for children with gonadotropin-releasing hormone (GnRH)-dependent early puberty that follows the normal pubertal pattern and the normal control mechanisms through GnRH. Central precocious puberty can be idiopathic or caused by organic conditions such as a central nervous system (CNS) tumor. GnRH-independent isosexual precocity or peripheral precocious puberty is caused by excessive estrogen secretion in girls or androgen secretion in boys from sources other than the GnRH-gonadotropin axis (such as the gonads or the adrenal glands) or by ectopic human chorionic gonadotropin (hCG) secretion. Exogenous sources of sex steroids will also cause peripheral precocious puberty. Pituitary gonadotropins are suppressed by negative feedback in all forms of peripheral precocious puberty because sex steroid secretion is autonomous. Contrasexual (or heterosexual) precocity refers to girls who virilize and boys who feminize.
As discussed in Chapter 533, the onset of normal puberty can be as early as 7 years of age among Caucasian girls and as early as 6 years of age among African American girls if they have high body mass index values. However, any girl with pubertal onset prior to age 8 years must be considered for underlying disease such as a CNS tumor. A girl who has rapid pubertal development, menarche prior to age 9, or neurologic signs or other findings of disease must not be considered normal prior to a thorough evaluation. Among boys, the earliest limit of normal puberty is 9 years of age. In any case in which a concern arises, an investigation is warranted. The classification scheme and causes of precocious puberty are outlined in Table 534-1.
TABLE 534-1A CLASSIFICATION SCHEME FOR PRECOCIOUS PUBERTY |Favorite Table|Download (.pdf) TABLE 534-1A CLASSIFICATION SCHEME FOR PRECOCIOUS PUBERTY
Central (or complete) isosexual precocious puberty (GnRH-dependent sexual precocity or premature activation of the hypothalamic pulse generator)
Familial or constitutional central precocious puberty
Idiopathic true precocious puberty
Other CNS disorders
Peripheral (or incomplete) isosexual precocity (hypothalamic GnRH independent)