Early Puberty in Boys: Causes and Symptoms

What is Early Puberty?

Early puberty is when your son starts showing the first signs of puberty before he is 9 years old. This can be normal, but might require evaluation by a pediatric endocrinologist (hormone doctor).

What is Normal Puberty?

Normal puberty is when children’s bodies start to grow and develop into young adult bodies. Boys usually start to go through puberty between the ages of 9-14 years. When your son starts to go through puberty, his gonads (testes) and adrenal glands (glands that sit on top of the kidneys) release hormones. These hormones cause the first signs of puberty, which are an increase in the size of the testes and length of the penis, body odor, underarm hair, pubic hair and acne (pimples). Over time, boys will develop later signs of puberty, such as increased muscle mass, stronger bones, voice deepening and a growth spurt.

There are 2 types of puberty that make up the entire pubertal process. These are:

• Adrenal puberty
  This is when the adrenal glands make hormones that cause the first signs of puberty; body odor, underarm hair, pubic hair and acne (pimples).
• Gonadal puberty
  This is when the pituitary gland (a small gland in the brain that controls other glands in the body) makes hormones (FSH and LH) that tell the testes to increase in size and make testosterone.

What Causes Early Puberty?

The causes of early adrenal puberty and early gonadal puberty are different.

Early adrenal puberty: Sometimes, early adrenal puberty is normal. Other times, a problem with the adrenal glands can cause your son to have early adrenal puberty.

Early gonadal puberty: There are 2 types of early gonadal puberty, which have different causes. These are:

• Gonadotropin dependent puberty
  This type of puberty is caused by the pituitary gland making the hormones FSH and LH, which tell the testes to make testosterone. This can be caused by tumors, radiation or trauma in the central nervous system or can be idiopathic. This means we have not found a cause of the early gonadal puberty.
• Gonadotropin independent puberty
  This type of puberty is caused by the testes working on their own or exposure to medication or products with hormones in them.

Rev. 1/2015. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.