Puberty and Gonadal Disorders
Normal puberty
Puberty begins with increased GnRH pulsatility, then LH/FSH, then gonadal steroids. In girls, thelarche is usually first, then pubic hair, growth spurt, and menarche. In boys, testicular enlargement is first, then pubic hair, penile growth, and voice change. Tanner staging documents progression. Central precocious puberty is GnRH-dependent; peripheral precocity is GnRH-independent. Bone age is advanced in both. In central precocious puberty, GnRH stimulation produces a pubertal LH response; MRI is warranted in boys and in girls with very early or rapid progression. Delayed puberty is absence of breast development by 13 in girls or testicular enlargement by 14 in boys.
Traps
Isolated premature thelarche or adrenarche is usually benign and not progressive. Do not treat slowly progressing puberty without confirming progression. In delayed puberty, distinguish constitutional delay, with delayed bone age and family history, from hypogonadotropic hypogonadism and hypergonadotropic hypogonadism such as Turner or Klinefelter syndrome. PCOS causes hyperandrogenism and irregular menses, not true precocity.
Worked example
An 8-year-old girl has breast budding, growth acceleration, and bone age 11. Basal LH is pubertal and GnRH stimulation shows a pubertal response. This is central precocious puberty; treat with a GnRH agonist and monitor growth and puberty. If her bone age were normal and growth slow, observe.