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What is Puberty? Puberty is the process that children undergo to develop into adults, with physical and sexual development. During puberty, children grow taller, gain muscle and weight, develop a strong skeleton, and graduate through predictable stages of behavior and brain development. These changes occur through the action of estrogens and androgens - female and male hormones - on the body.
Where are estrogens and androgens made? These hormones are made in ovaries and adrenal glands in girls, and testicles and adrenal glands in boys. Ovaries and testicles also make eggs and sperm, and the adrenal glands also produce adrenaline, energy and salt balance hormones. Ovaries and testicles each produce estrogens and testosterone, but in different balances. Boys produce 10-20 times the amount of testosterone that girls do, which accounts for greater facial and body hair and musculature. Girls produce relatively more estrogens, which accounts for breast, hip and vaginal development. Adrenal glands are located just above the kidneys, and are responsible for the development of underarm odor and pubic hair by way of adrenal androgens, or male hormones.
At what age does puberty start? Ovaries and testicles start maturing at some point between 8-14 years old, in most children. When pubertal signs are present before 8 years old in a girl, or 9 years old in a boy, puberty is considered early, or precocious. When it's only pubic hair or odor, it is more often due to maturation of the adrenal glands, which is called precocious at these same ages, but due to different origin of hormone, has a separate diagnosis - called precocious - or premature - adrenarche, or early adrenal gland maturation.
What causes puberty to start? Scientists aren't sure precisely what triggers the process of puberty to start, but it is clear that a few proteins in the hypothalamic area of the brain start rising in coordinated pulses to tell the pituitary gland to, in turn, secrete LH and FSH hormones. As levels of LH and FSH are released in a regular tempo, and rise overall, they cause the growth of the gonads - ovaries and testicles - and the maturation of the hormone producing cells within them. These hormones - estrogens and androgens - fuel the body's changes. Pubertal changes typically span about 4-5 years from beginning to end, with the majority of growth and change in development within the first 2-3 years.
What is precocious puberty? What is late puberty? When puberty starts early (before 8 years in girls, or 9 years in boys), or proceeds rapidly - or if it hasn't yet started by the time a child is approaching 14 years old - then blood tests are usually run to find out if the child is simply an early or late bloomer, or if there is a medical reason for these changes to have occurred early or to be delayed. Early or late pubertal timing often occur within families at similar ages. But exposure to hormones in the environment, contact with adult creams to supplement hormonal levels, and an abnormally slow thyroid gland (learn more here) can all cause the appearance of puberty, even if it is not present. True precocious puberty may be due to a pituitary or brain growth. Late puberty can be caused by thyroid dysfunction, as well as other autoimmune or nutrition concerns, or potentially, dysfunction of the pituitary itself.
How can you tell if a child is in puberty? An endocrinologist evaluates for puberty with a careful examination, rates of growth, blood tests, and a "bone age" x-ray - an evaluation of the maturity of a child's skeleton, to determine if: 1. there is true early or late puberty, and 2. if there are health concerns related to it.
What is Tanner Stage? Endocrinologists and pediatricians communicate a child's development by their "Tanner stage", which refers to their pattern of pubic hair, and breast development or testicular size. Stage I is a child's stage before puberty starts, and Stage V is adult maturity.
How does puberty affect growth? Children typically follow the same percentile from about age 2 to the onset of puberty. When there is deviation from their original trajectory, it is often due to weight changes and puberty. The production of estrogen and testosterone cause an increase in the rate of growth, maturation of the skeleton, and accrual of bone density. Since normal puberty starts between 8-14 in most children, that is when we'd expect to see a growth spurt, with an average onset of the growth spurt between 10 and 10 1/2 for girls, and 12-12 1/2 for boys. Growth spurts average about 3 1/2 inches per year, with shorter children typically having a slower peak growth velocity, and taller children with more rapid growth. Growth typically slows about 2 years following the onset of the growth spurt, with growth complete for most girls by 15 years, and for boys by 17 years.
More detailed information about children's growth can be found here.
If there is clear early or late puberty, then there are treatment options available to suppress it from progressing, or to stimulate puberty to start. These options should be discussed with your pediatrician, and if available, a pediatric endocrinologist.
Why does my child have precocious puberty? The vast majority of girls who have early puberty develop at a young age without any known reason. It often runs in families, but subtle pressure shifts within the brain - due to benign cysts or growths called microadenomas - may not cause any true health concern other than stimulating puberty to start at a young age. In boys, early puberty is also often familial, but less often than in girls. When it isn't, a more comprehensive evaluation is performed, to try and figure out the reason why, and address that cause.
Why does my child have late puberty? In constitutional delay, there is also frequently a family history of delayed onset of puberty. When there is not, it is important to check for health conditions that may cause just enough inflammation or hormone/nutritional deficiency to prevent a teenager from starting or progressing through puberty. Rarely, there is a genetic cause of absent puberty.
What treatment is available for precocious puberty? Precocious puberty is suppressed by high doses of GnRH agonists, either by injection every 1-6 months (depending on the formulation), or through an implant under the skin in the upper arm. All use the same hormonal ingredient that prevents pulses of gonadotrophins (LH and FSH), to be secreted. By reducing the pulses, there is less responsiveness to, and a reduced amount of, LH and FSH in the body, so that estrogen and testosterone production is reduced to prepubertal levels. Children are generally treated with puberty suppression through the age of a typical onset of puberty.
Are there risks to puberty suppression? GnRH agonist treatment has been used for decades, with only its formulation changed to allow less frequent injections. Long-term (20 year) safety data have been published on the original formulation, which report no increased risk for cancer, diabetes, or infertility. That said, it is a painful injection, along with a very low possibility of allergy or infection. Rarely, a firm lump develops at the injection site, which is the result of inflammation against components of the medication. This is called a "sterile abscess" and most often goes away over time. Very rarely, there can be calcium deposited in it that requires its removal.
The largest concern is for the development of weak bones, or osteoporosis. This is due to the powerful effects on bone-building that pubertal hormones provide. If puberty is precocious, and treatment during years younger than the average onset of puberty, then treatment is unlikely to cause osteoporosis in later life. But if the treatment extends through typical ages of puberty, then the risk of future bone fragility increases due to fewer years available for the skeleton to build. To help offset this risk, endocrinologists strongly recommend that children take enough Vitamin D3 for normal levels, consume 2-4 servings of calcium-rich foods daily, and participate in regular weight-bearing exercise.
What treatment is available for delayed puberty? For boys, a jump start of 3-6 monthly injections of testosterone will often prompt puberty to continue on its own. For girls, it is less common to give estrogen, but if no other cause of delayed puberty is found - including a genetic evaluation - then this option is possible, through pills or patches. Because this estrogen and testosterone suppresses the body's own production of hormones, reevaluation of puberty should take place at least one month following the last treatment. Risks are few, but the greatest risk involves a thorough investigation of concerns that could be delaying puberty, and addressing those appropriately and sensitively.
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