Disorders of pubertal development.

Puberty is the period of life during which reproductive capability is acquired. It is characterized clinically by the acquisition of secondary sexual characteristics associated with a growth spurt, and on average takes 3-4 years. Early maturation is defined as the development of sexual characteristics before the age of 8 years in girls and 9 years in boys. Delayed puberty is defined when there are no signs of puberty at the age of 13.4 years in girls and 14 years in boys (2 SD above the mean of chronological age for the onset of puberty). There are many forms of premature sexual maturation: gonadotrophin-dependent (central, or 'idiopathic' or 'true' precocious puberty) and gonadotrophin-independent precocious puberty (McCune-Albright syndrome in girls, testotoxicosis in boys); isolated premature thelarche (in the forms of classical, atypical and variant); premature adrenarche (characterized by the production of significant quantities of androgens between 5 and 8 years of age); premature menarche. The differential diagnosis of delayed puberty is between constitutional delay of growth and puberty, pubertal delay secondary to chronic disease and hypogonadotrophic hypogonadism.