DESCRIPTION

• In most populations, puberty onset mean ages are 10.5 years for girls and 11.5 years for boys. At least in girls, the mean age of onset of puberty appears to be decreasing (8.9 years in Black girls, 10 years for White girls).
  • Girls: The first sign of puberty is most commonly breast development (thelarche), followed by pubic hair (pubarche), and then menarche. Menarche generally occurs 2 to 3 years after thelarche.
  • Boys: The first sign of puberty is usually testicular enlargement, followed by pubarche, and penile growth.
• Definitions
  • Precocious puberty has traditionally been defined as physical signs of sexual development before age 8 years in girls and age 9 years in boys (2 to 2.5 standard deviations below the mean age of onset of puberty).
  • 1999 Pediatric Endocrine Society guidelines proposed lowering the age considered to be normal for sexual development in girls to as young as age 6 years in Black girls and age 7 years in White girls. These guidelines have not been universally adopted, and most primary care providers adhere to the traditional definitions.
  • Thelarche onset in 7- to 8-year-old females is increasingly common and frequently associated with obesity. Despite the apparent decline in the mean age of thelarche, the mean age of menarche (12 to 12.5 years) has only declined modestly over the past 30 years.
  • Pubertal onset in boys may also be declining, but no changes have been recommended to the traditional thresholds for diagnosis of precocious puberty.
• When evaluating precocious puberty, the entire clinical picture must be considered, including the rate of pubertal progression and the presence of any neurologic symptoms.

EPIDEMIOLOGY

• Occurs in ~1 in 5,000 to 10,000 children
• Up to 10 times more common in girls than boys; this could be related to referral bias.
• In girls: ~90% of central precocious puberty is idiopathic.
• In boys: precocious puberty is more likely associated with underlying pathology.
  • 25–60% of boys have idiopathic central precocious puberty.
• The pathologic etiologies are similar between boys and girls.
• Racial differences observed in girls: Black girls may enter puberty 1 year sooner on average than White girls.
• Increased incidence in internationally adopted children and in children born premature or small for gestational age
• Increased incidence in children living with obesity
• Increased risk if there is a family history of central precocious puberty
• Increased incidence in children with intracranial disturbances (e.g., structural central nervous system [CNS] abnormality such as tumor, prior trauma, irradiation, cerebral palsy)
• Increased incidence in children with previous steroid exposure (e.g., poorly controlled congenital adrenal hyperplasia)

ETIOLOGY

• Central precocious puberty (gonadotropin-releasing hormone [GnRH] dependent)
  • Associated with gonadotropin (LH and/or follicle-stimulating hormone [FSH]) levels elevated beyond the normal prepubertal range; results from activation of hypothalamic-pituitary-gonadal axis
  • Physical changes are typically those of normal puberty for a child of that sex.
• Peripheral sex hormone effects (peripheral precocious puberty or GnRH-independent; less common)
  • Gonadotropin-independent elevation of sex steroids arising (i) directly from gonads and/or adrenals, (ii) through stimulation of gonads by GnRH-independent mechanism, or (iii) from an exogenous source
  • Physical changes reflect predominant excess hormones (estrogenic or androgenic) and are often markedly discordant from normal pubertal development.

RISK FACTORS

PATHOPHYSIOLOGY

• Central precocious puberty
  • Results from hypothalamic-pituitary-gonadal axis activation
  • Outside of being earlier than typical puberty, follows the normal pattern and timing of pubertal events
  • In many cases, this is idiopathic, especially in girls.
• Peripheral precocious puberty
  • Arises from peripheral sex hormone sources, including gonadal and adrenal disorders, abdominal or pelvic tumors, or exogenous sex steroids
  • Can progress to central precocious puberty due to maturation of the hypothalamic-pituitary axis by sex steroids