Precocious puberty in girls is when the following happens before the age of 8:
- Progressive breast development with menstruation beginning two to three years after
- Accelerated growth
Precocious puberty in boys is when the following happens before the age of 9:
- Penile enlargement
- Testicular development
- Increased muscle development
- Voice change
- Growth of body hair
- Accelerated growth
There are two types of precocious puberty:
- Central precocious puberty (CPP). Central precocious puberty is when the normal process of puberty starts too early. Most of the time there is no underlying medical cause. Less commonly, CPP may be caused by an abnormal pituitary gland or a problem with the hypothalamus.
- Peripheral precocious puberty (PPP). Peripheral precocious puberty occurs when the sex hormone glands (adrenal glands in boys and girls, ovaries in girls and testes in boys) begin functioning earlier than normal. This type of precocious puberty is less common. Reasons the adrenals, ovaries and testes may begin to function earlier than normal include:
- An adrenal tumor that secretes estrogen (hormones that promote the development of female characteristics) or testosterone (a steroid hormone that promotes the development of male characteristics)
- A genetic abnormality called congenital adrenal hyperplasia (CAH) that causes the adrenal glands to make too much androgen (hormones that promote the development of male characteristics)
- Exposure to medicines, creams, ointments or supplements that contain estrogen, androgen or testosterone
- Ovarian cysts or ovarian tumors in girls
- Tumors in the testicles in boys
There are two common forms of precocious puberty that do not require any treatment:
- Premature thelarche. Premature thelarche causes a small amount of breast development in girls without any other changes of puberty. The breast development does not progress and eventually goes away. This often occurs in toddler girls.
- Premature adrenarche. Premature adrenarche occurs when the normal secretion of androgens from the adrenal glands begins unusually early. This leads to small amounts of pubic hair and adult body odor in boys and girls, which increase very slowly. No other signs of puberty are usually present. These changes progress so slowly that the children do not need treatment.
Diagnosis of Precocious Puberty
If your child is developing faster than normal, it may be due to precocious puberty. Doctors at Riley at IU Health can perform the following exams and tests to make a diagnosis:
- Physical exam. The doctor can compare your child's growth and pubertal development with the growth and pubertal development of children of the same age and gender.
- Blood test. A blood test may be used to check pituitary hormones, sex hormone levels (estradiol or testosterone) and other hormones. The doctor may inject your child with the synthetic hormone leuprolide before measuring these hormones. Leuprolide makes it easier to interpret the results of your child’s test.
- Bone age test. Your child’s doctor may perform a bone age test, which is an X-ray of the left hand and wrist. This test can show how far along in puberty your child is and may show if early puberty will affect your child’s height as an adult.
- Magnetic resonance imaging (MRI). If a blood test indicates central precocious puberty, the doctor may perform a MRI scan of the brain to look for an abnormality in the pituitary gland.