Precocious puberty is sexual maturation that begins before age 9 in boys or before age 8 in girls.
- The cause of precocious puberty is often unknown, but it may be caused by structural abnormalities or tumors in the brain.
- Symptoms include an early growth spurt and early development of pubic and underarm hair.
- The diagnosis is based on x-rays, blood tests, and imaging tests.
Treatment depends on the type of precocious puberty but may include hormone therapy.
Normal puberty is a sequence of events in which physical changes occur, resulting in adult physical characteristics and the capacity to reproduce. Normally, these changes occur sequentially during puberty, resulting in sexual maturity.
The start of puberty takes place when the hypothalamus (the region of the brain that controls the pituitary gland) begins to secrete a chemical signal called gonadotropin-releasing hormone. The pituitary gland responds to this signal by releasing hormones called gonadotropins (luteinizing hormone and follicle-stimulating hormone), which stimulate the growth of the sex glands (the testes in boys and the ovaries in girls). These sex glands secrete sex hormones, such as testosterone or estrogen, that cause puberty.
In boys, the first signs of puberty are enlargement of the testes and scrotum, followed by lengthening of the penis. Pubic and underarm hair (axillary hair) appear next. In boys, puberty usually begins between the ages of 10 years and 14 years (see Puberty in Boys).
In girls, the first change of puberty is usually the start of breast development (breast budding). Shortly afterward, pubic and underarm hair begin to grow. In girls, puberty usually begins between the ages of 8 to 13 years .
During puberty, sexual development occurs in a set sequence. However, when the changes begin and how quickly they occur vary from person to person.
For girls, puberty begins around age 8 to 13 years and lasts about 4 years.
For boys, puberty begins around age 10 to 14 years and lasts about 3 years.
The chart shows a typical sequence and normal range of development for the milestones of sexual development.
In both sexes, around the time of puberty, the adrenal gland also begins to secrete hormones that lead to the appearance of pubic and underarm hair. These adrenal hormones are controlled by different chemical signals than the other puberty hormones.
By Andrew Calabria , MD, Perelman School of Medicine at The University of Pennsylvania