Precocious Puberty

Precocious puberty describes secondary sexual characteristics that appear before age 8 years in girls or before age 9 years in boys. These age cutoffs remain clinically useful, but they are not a diagnosis by themselves. Puberty has trended earlier in some populations, and the child’s age, pattern of development, rate of change, growth velocity, and neurologic findings matter more than a single finding on one visit. Central precocious puberty (CPP) is early reactivation of the hypothalamic-pituitary-gonadal (HPG) axis. Pulsatile gonadotropin-releasing hormone (GnRH) stimulates pituitary release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The gonads then produce estrogen or testosterone, creating a pubertal sequence that is usually developmentally consonant. In a girl, this may begin with progressive breast development, followed by an acceleration in linear growth and later pubic hair, body changes, and menstruation. In a boy, bilateral testicular enlargement is usually the earliest sign, followed by penile growth, pubic hair, growth acceleration, and voice change. Peripheral precocious puberty is GnRH-independent. Sex steroids are produced outside the normal central pubertal pathway, so LH and FSH are generally suppressed. Causes include...