Puberty is the time in life when a boy or girl becomes sexually mature. It is a process that usually happens between ages 10 and 14 for girls and ages 12 and 16 for boys. It causes physical changes, and affects boys and girls differently.

In girls:

• The first sign of puberty is usually breast development.
• Then hair grows in the pubic area and armpits.
• Menstruation (or a period) usually happens last.

In boys:

• Puberty usually begins with the testicles and penis getting bigger.
• Then hair grows in the pubic area and armpits.
• Muscles grow, the voice deepens, and facial hair develops as puberty continues.

Both boys and girls may get acne. They also usually have a growth spurt (a rapid increase in height) that lasts for about 2 or 3 years. This brings them closer to their adult height, which they reach after puberty.

The time in one's life when sexual maturity takes place is known as puberty. The physical changes that mark puberty typically begin in girls between ages 8 and 13 and in boys between ages 9 and 14.

Precocious puberty is a condition that occurs when sexual maturity begins earlier than normal. Precocious (meaning prematurely developed) puberty begins before age 8 for girls and before age 9 for boys.

Children affected by precocious puberty may experience problems such as:

• Failure to reach their full height because their growth halts too soon
• Psychological and social problems, such as anxiety over being "different" from their peers. However, many children do not experience major psychological or social problems, particularly when the onset of puberty is only slightly early.

Delayed puberty is the term for a condition in which the body's timing for sexual maturity is later than the normal range of ages.

Many children with delayed puberty will eventually go through an otherwise normal puberty, just at a late age. Other children have a long-lasting condition known as hypogonadism (pronounced HI-poe-GO-nad-iz-uhm) in which the sex glands (the testes in men and the ovaries in women) produce few or no hormones. For example, hypogonadism can occur in girls with Turner syndrome or in individuals with hypogonadotropic (pronounced HI-po-GO-nah-doe-TROH-pik) hypogonadism, which occurs when the hypothalamus (pronounced HI-po-THAL-uh-muss) produces little to no gonadotropin-releasing hormone (pronounced goh-nad-uh-TROH-pin) (GnRH).

Delayed puberty is characterized by the lack of onset of puberty within the normal range of ages.

In Girls

The signs of puberty include:

• Growth of pubic and other body hair
• Growth spurt
• Breast development
• Onset of menstruation (after puberty is well advanced)
• Acne

In Boys

The signs of puberty include:

• Growth of pubic hair, other body hair, and facial hair
• Enlargement of testicles and penis
• Muscle growth
• Growth spurt
• Acne
• Deepening of the voice

Many children with delayed puberty will eventually go through an otherwise normal puberty, just at a late age. Sometimes, this delay occurs because the child is just maturing more slowly than average, a condition called constitutional delay of puberty. This condition often runs in families.

Puberty can be delayed in children who have not gotten proper nutrition due to long-term illnesses. Also, some young girls who undergo intense physical training for a sport, such as running or gymnastics, start puberty later than normal.

In other cases, the delay in puberty is not just due to slow maturation but occurs because the child has a long-term medical condition known as hypogonadism (pronounced HI-poe-GO-nad-iz-uhm), in which the sex glands (the testes in men and the ovaries in women) produce few or no hormones. Hypogonadism can be divided into two categories: secondary hypogonadism and primary hypogonadism.

• Secondary hypogonadism (also known as central hypogonadism or hypogonadotropic hypogonadism), is caused by a problem with the pituitary gland or hypothalamus (part of the brain). In secondary hypogonadism, the hypothalamus and the pituitary gland fail to signal the gonads to properly release sex hormones. Causes of secondary hypogonadism include:
  • Kallmann syndrome, a genetic problem that also diminishes the sense of smell
  • Isolated hypogonadotropic hypogonadism, a genetic condition that only affects sexual development but not the sense of smell
  • Prior radiation, trauma, surgery, or other injury to the brain or pituitary
  • Tumors of the brain or pituitary
• In primary hypogonadism, the problem lies in the ovaries or testes, which fail to make sex hormones normally. Some causes include:
  • Genetic disorders, especially Turner syndrome (in women) and Klinefelter syndrome (in men)
  • Certain autoimmune disorders
  • Developmental disorders
  • Radiation or chemotherapy
  • Infection

To identify whether a child is entering puberty, a pediatrician (a physician specializing in the treatment of children) will carefully examine the following:

• In girls, the growth of pubic hair and breasts
• In boys, the increase in size of the testicles and penis and the growth of pubic hair

The pediatrician will compare what he or she finds against the Tanner scale, a 5-point scale that gauges the extent of puberty development in children.

To diagnose hypogonadotropic hypogonadism, a healthcare provider may prescribe these tests:

• Blood tests to measure hormone levels
• Blood tests to measure if the pituitary gland can correctly respond to GnRH
• An MRI of the brain and pituitary gland

With delayed puberty or hypogonadism, treatment varies with the origin of the problem but may involve:

• In males, testosterone injections, skin patches, or gel
• In females, estrogen and/or progesterone given as pills or skin patches