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Causes
By Mayo Clinic staffTo understand what causes precocious puberty in some children, it's helpful to know what causes puberty to begin. A complex process known as the hypothalamic-pituitary-gonadal (HPG) axis governs when puberty occurs. This process involves the following steps:
- Your brain starts the process. Part of your brain called the hypothalamus makes gonadotropin-releasing hormone (Gn-RH).
- The pituitary gland releases more hormones. Gn-RH causes your pituitary gland — a small bean-shaped gland at the base of your brain — to release two more hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- Sex hormones are produced. LH and FSH cause the ovaries to produce hormones involved in the growth and development of female sexual characteristics (estrogen) and the testicles to produce hormones responsible for the growth and development of male sexual characteristics (testosterone). The adrenal glands also begin to make estrogen and testosterone.
- Physical changes occur. The production of estrogen and testosterone causes the physical changes of puberty.
The reason this process begins early in some children depends on the type of precocious puberty they have: central precocious puberty or peripheral precocious puberty.
Central precocious puberty
There's usually no identifiable cause for this type of precocious puberty.
In central precocious puberty, the entire HPG axis starts too soon. Although they begin earlier than they should, the pattern and timing of the steps in the process are otherwise normal. For the majority of children with this condition, there's no underlying medical problem and no identifiable reason for the HPG axis to begin when it does.
In rare cases, the following may cause central precocious puberty:
- A tumor in the brain or spinal cord (central nervous system)
- An infection, such as encephalitis or meningitis
- A defect in the brain present at birth, such as excess fluid buildup (hydrocephalus) or a noncancerous tumor (hamartoma)
- Radiation to the brain or spinal cord
- Injury to the brain or spinal cord
- An obstruction of blood flow to the brain (ischemia)
- McCune-Albright syndrome — a genetic disease that affects bones and skin color and causes hormonal problems
- Congenital adrenal hyperplasia — a group of inherited disorders involving abnormal hormone production by the adrenal glands
- Hypothyroidism — a condition in which the thyroid gland doesn't produce enough hormones
Peripheral precocious puberty
Estrogen or testosterone in your child's body causes this type of precocious puberty.
Peripheral precocious puberty, which is less common than central precocious puberty, happens without involvement of Gn-RH. Instead, the cause is release of estrogen or testosterone into the body because of problems with the ovaries, testicles, adrenal glands or pituitary gland.
In both girls and boys, the following may lead to peripheral precocious puberty:
- A tumor in the adrenal glands or in the pituitary gland that secretes estrogen or testosterone
- McCune-Albright syndrome
- Exposure to external sources of estrogen or testosterone, such as creams or ointments
In girls, peripheral precocious puberty may also be associated with:
- Ovarian cysts
- Ovarian tumors
In boys, peripheral precocious puberty may also be caused by:
- A tumor in the cells that make sperm (germ cells) or in the cells that make testosterone (Leydig cells)
- Gene mutation — a rare disorder called familial gonadotropin-independent sexual precocity, which is caused by a defect in a gene, can result in the early production of testosterone in boys, usually between ages 1 and 4.
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- Pralong FP. Diagnosis and treatment of delayed puberty. http://www.uptodate.com/home/index.html. Accessed Oct. 13, 2008.
- Saenger P. Overview of precocious puberty. http://www.uptodate.com/home/index.html. Accessed Oct. 13, 2008.
- Carel JC, et al. Precocious puberty. New England Journal of Medicine. 2008;358:2366.
- Muir A. Precocious puberty. Pediatrics in Review. 2006;27:373.
- Precocious puberty. The Hormone Foundation. http://www.hormone.org/Resources/Growth/upload/bilingual_precocious_puberty.pdf. Accessed Nov. 24, 2008.
- Styne D. Precocious puberty (sexual precocity). In: Gardner DG, et al. Greenspan's Basic & Clinical Endocrinology. 8th edition. New York, N.Y.: McGraw-Hill; 2007. http://www.accessmedicine.com/content.aspx?aID=2631040&searchStr=precocious+puberty. Accessed Nov. 11, 2008.
