Precocious puberty (early puberty)

Precocious puberty is a medical term for puberty occurring at an unusually early age. In most of these children the process is normal in every respect except the unusually early age, and simply represents a variation of normal development. In a minority of children the early development is triggered by a disease such as a tumor or injury of the brain. Even in instances where there is no disease, unusually early puberty can have adverse effects on social behavior and psychological development, can reduce adult height potential, and may shift some life-long health risks. Central precocious puberty can be treated by suppressing the pituitary hormones that induce sex steroid production.

The term is used with several slightly different meanings that are usually apparent from the context. In its broadest sense, "precocious puberty" sometimes refers to any physical sex hormone effect, due to any cause, occurring earlier than the usual age, especially when it is being considered as a medical problem. Stricter definitions of "precocity" may refer only to central puberty starting before a statistically specified age based on percentile in the population (e.g., 2.5 standard deviations below the population mean), on expert recommendations of ages at which there is more than a negligible chance of discovering an abnormal cause, or based on opinion as to the age at which early puberty may have adverse effects. A common definition for medical purposes is onset before 8 years in girls or 9 years in boys. As most children with precocious puberty have no disease, all of these definitions are somewhat arbitrary and based on social values.

Terminology

The term is used with several slightly different meanings that are usually apparent from the context.

• In its broadest sense, "precocious puberty" sometimes refers to any physical sex hormone effect, due to any cause, occurring earlier than the usual age, especially when it is being considered as a medical problem.
• Stricter definitions of "precocity" may refer only to central puberty starting before a statistically specified age based on percentile in the population (e.g., 2.5 standard deviations below the population mean), on expert recommendations of ages at which there is more than a negligible chance of discovering an abnormal cause, or based on opinion as to the age at which early puberty may have adverse effects. A common definition for medical purposes is onset before 8 years in girls or 9 years in boys.
• As most children with precocious puberty have no disease, all of these definitions are somewhat arbitrary and based on social values.

Classification

Early pubic hair, breast, or genital development may result from natural early maturation or from several other conditions.

Central

If the cause can be traced to the hypothalamus or pituitary, the cause is considered central.

Causes can include:

• damage to the inhibitory system of the brain is damaged (due to infection, trauma, or irradiation)
• hypothalamic hamartoma produces pulsatile gonadotropin-releasing hormone (GnRH)
• Langerhans cell histiocytosis

If no cause can be identified, it is considered idiopathic or constitutional.

Peripheral

Secondary sexual development induced by sex steroids from other abnormal sources is referred to as peripheral precocious puberty or precocious pseudopuberty.

Causes can include:

Endogenous sources

• gonadal tumors (such as arrhenoblastoma)
• adrenal tumors
• germ cell tumor
• congenital adrenal hyperplasia
• McCune–Albright syndrome

Exogenous hormones

• Environmental
• As treatment for another condition

Bisphenol A (BPA) is a chemical used in hard plastics, and is frequently used to make baby bottles, water bottles, sports equipment, and medical devices. It is also in an epoxy used as a coating in almost all food and beverage cans in most countries. Scientists are concerned about BPA's behavioral effects on fetuses, infants, and children at current exposure levels because it can affect the prostate gland or mammary gland, and lead to early puberty in girls, and possibly cancer later in life. BPA mimics and interferes with the action of estrogen, which is an important reproduction and development regulator. It leaches out of plastic into liquids and foods.

Many causes of early puberty are somewhat unclear, though girls who have a high-fat diet and are not physically active or are obese are more likely to physically mature earlier. Exposure to chemicals that mimic estrogen (known as xenoestrogens) is a possible cause of early puberty in girls.

In a study using neonatal melatonin on rats, results suggest that elevated melatonin could be responsible for some cases of early puberty.

Clinical and social significance

Medical evaluation is sometimes necessary to recognize the few children with serious conditions from the majority who have entered puberty early but are still medically normal. Early sexual development deserves evaluation because it may:

1. induce early bone maturation and reduce eventual adult height
2. indicate the presence of a tumor or other serious problem
3. cause the child, particularly a girl, to become an object of adult sexual interest

Earlier puberty is believed to put girls at higher risk of sexual abuse, teasing or bullying, mental health disorders and short stature as adults. Helping children control their weight is suggested to help delay puberty. Early puberty additionally puts girls at a "far greater" risk for breast cancer later in life. Girls as young as 8 are increasingly starting to menstruate, develop breasts and grow pubic and underarm hair; these "biological milestones" only typically occurred at 13 or older decades ago. African American girls are especially prone to early puberty. There are theories debating the trend of early puberty, but the exact causes are not known. "This is a review of what we know; it's absolutely superb," said Dr. Marion Kavanaugh-Lynch, an oncologist and director of the California Breast Cancer Research Program in Oakland, which directs tobacco tax proceeds to research projects. "The data indicates that if you get your first period before age 12, your risk of breast cancer is 50 percent higher than if you get it at age 16," said the report's author, biologist Sandra Steingraber, herself a cancer survivor. "For every year we could delay a girl's first menstrual period, we could prevent thousands of breast cancers."

Though boys face fewer problems upon early puberty than girls, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them. Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their cognitive and social development may lag behind their appearance. Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.

Central precocious puberty can be caused by intracranial neoplasm, infection, trauma, hydrocephalus, and Angelman syndrome. Bones can be considered older in individuals with early puberty. Early puberty is marked by growth hormone problems resulting from various brain disorders. Precocious puberty can make a child able to conceive when very young; the youngest mother on record is Lina Medina, who gave birth at the age of 5 years, 7 months and 21 days.

High levels of beta-hCG in serum and cerebrospinal fluid observed in a 9-year-old boy suggest a pineal gland tumor. The tumor is called a chorionic gonadotropin secreting pineal tumor. Radiography and chemotherapy reduced tumor and beta-hCG levels normalized. "Central precocious puberty (CPP) was reported in some patients with suprasellar arachnoid cysts(SAC), and SCFE occurs in patients with CPP because of rapid growth and changes of growth hormone secretion."

Diagnostic criteria

Studies indicate that breast development in girls and pubic hair in girls and boys are starting earlier than in previous generations. As a result, "early puberty" in children, particularly girls, as young as 9 and 10 is no longer considered abnormal, although it may be upsetting to parents and can be harmful to children who mature physically at a time when they are immature mentally.

No single age limit reliably separates normal from abnormal processes in children today, but the following age thresholds for evaluation will minimize the risk of missing a significant medical problem:

• Pubic hair or genital enlargement in boys with onset before 9.5 years.
• Breast development in boys before appearance of pubic hair and testicular enlargement.
• Pubic hair before 8 or breast development in girls with onset before 7 years.
• Menstruation in girls before 10 years.

Treatment

One possible treatment is with anastrozole. Histrelin acetate (Supprelin) or Leuprolide, both GnRH agonists, may also be used. GnRH agonists stimulate the pituitary to release Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). However, when used regularly, GnRH agonists cause a decreased release of FSH and LH. GnRH produced by the hypothalamus is pulsatile, allowing for a physiologic release of FSH and LH.