Practice Essentials
Precocious puberty refers to the appearance of physical and hormonal signs of pubertal development at an earlier age than is considered normal. For many years, puberty was designated as precocious in girls younger than 8 years; however, studies have come to indicate that signs of early puberty (breasts and pubic hair) are often present in girls (particularly Black girls) between ages 6-8 years. For boys, onset of puberty before age 9 years is still considered precocious.
In central precocious puberty (CPP), which is gonadotropin-dependent, early maturation of the entire hypothalamic-pituitary-gonadal (HPG) axis occurs, with the full spectrum of physical and hormonal changes of puberty.
Premature adrenarche and premature thelarche are two common, benign, normal variant conditions that can resemble true precocious puberty but that progress slowly or not at all. Premature thelarche refers to the isolated appearance of breast development, usually in girls younger than 3 years; premature adrenarche refers to the appearance of pubic hair without other signs of puberty in girls or boys younger than 7-8 years. A thorough history, physical examination, and growth curve review can help to distinguish these normal variants from true sexual precocity. A review of this topic was published as an American Academy of Pediatrics clinical report.
Signs of precocious puberty
Precocious puberty in girls is characterized as follows:
The first and most obvious sign of early puberty is usually breast enlargement, which may initially be unilateral
Pubic and axillary hair may appear before, at about the same time as, or well after the appearance of breast tissue; axillary odor usually starts about the same time as the appearance of pubic hair
Menarche is a late event and does not usually occur until 2-3 years after onset of breast enlargement
The pubertal growth spurt occurs early in female puberty and usually is evident by the time of initial evaluation
Precocious puberty in boys is characterized as follows:
The earliest evidence of puberty is testicular enlargement, a subtle finding that often goes unnoticed by patients and parents
Growth of the penis and scrotum typically occurs at least a year after testicular enlargement
Accelerated linear growth (the pubertal growth spurt) occurs later in the course of male puberty than in female puberty but often takes place by the time other physical changes are noted
Workup in precocious puberty
Because of the development of more sensitive third-generation assays for luteinizing hormone (LH), which can detect levels as low as 0.1 IU/L or lower, random LH is now considered a good screening test for CPP, with levels of 0.3 IU/L or above considered diagnostic. However, many children with CPP have prepubertal basal LH levels but will respond to a challenge with gonadotropin-releasing hormone (GnRH) with an increase to 5 IU/L or above, which is considered pubertal.
Measurement of serum testosterone is useful in boys with suspected precocious puberty. Testosterone levels less than 30 ng/dL are in most cases prepubertal, while testosterone levels of 30-100 ng/dL are usually seen in cases where puberty is progressive and levels of greater than 100 ng/dL need further evaluation. For girls, estradiol measurements are usually elevated but are less reliable indicators of the stage of puberty.
Levels of adrenal androgens (eg, dehydroepiandrosterone [DHEA], DHEA sulfate [DHEA-S]) are usually elevated in boys and girls with premature pubarche. DHEA-S, the storage form of DHEA, is the preferred steroid to measure because its levels are much higher and vary much less during the day. In most children with premature pubarche, DHEA-S levels are 20-100 mcg/dL, whereas in rare patients with virilizing adrenal tumors, levels may exceed 500 mcg/dL.
When used to determine bone age, radiography of the hand and wrist is a quick and helpful means of estimating the likelihood of precocious puberty and its speed of progression. A bone age advanced by 2 years relative to chronologic age is considered significant.
Magnetic resonance imaging (MRI) is often recommended to look for a tumor or hamartoma after hormonal studies indicate a diagnosis of CPP but is very unlikely to reveal pathology related to CPP in girls between the ages of 6 and 8 years.
If the history, physical examination, and laboratory data suggest that a child exhibits early and sustained evidence of pubertal maturation, the clinician must differentiate CPP from precocious pseudopuberty. In CPP, which is gonadotropin-dependent, early maturation of the entire hypothalamic-pituitary-gonadal (HPG) axis occurs, with the full spectrum of physical and hormonal changes of puberty. Precocious pseudopuberty is much less common and refers to conditions in which increased production of sex steroids is gonadotropin-independent (see Precocious Pseudopuberty). Correct diagnosis of the etiology of sexual precocity is critical because the evaluation and treatment of patients with precocious pseudopuberty are quite different from those of patients with CPP.
Management
Early onset of puberty can cause several problems. The early growth spurt initially can result in tall stature, but rapid bone maturation can cause linear growth to cease too early and may result in short adult stature. The early appearance of breasts or menses in girls and increased libido in boys can cause emotional distress for some children. However, not all patients with CPP who are age 7 years or older at the time of onset require treatment. For patients with precocious puberty who are treated with GnRH agonists:
Follow-up should occur every 4-6 months to ensure that progression of puberty has been arrested
Favorable signs include normalization of accelerated growth, reduction (or at least no increase) in breast size, and suppression of gonadotropin levels after a challenge of GnRH
The ideal testing frequency has not been established
Monitor bone age yearly to confirm that advancement has slowed