Puberty
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Puberty is the process of physical changes through which a
On average, females begin puberty at ages 10–11 and complete puberty at ages 15–17; males generally begin puberty at ages 11–12 and complete puberty at ages 16–17.[1][2][3] The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12 and 13.[2] For males, first ejaculation, spermarche, occurs on average at age 13.[4] In the 21st century, the average age at which children, especially females, reach specific markers of puberty is lower compared to the 19th century, when it was 15 for females and 17 for males (with age at first periods for females and voice-breaks for males being used as examples).[5] This can be due to any number of factors, including improved nutrition resulting in rapid body growth, increased weight and fat deposition,[6] or exposure to endocrine disruptors such as xenoestrogens, which can at times be due to food consumption or other environmental factors.[7][8] However, more modern archeological research suggests that the rate of puberty as it occurs now is the intended way. Growth spurts began at around 10–12, but markers of later stages of puberty such as menarche had delays that correlated with severe environmental conditions such as poverty, poor nutrition, air and pollution.[9][10][11] Puberty that starts earlier than usual is known as precocious puberty, and puberty which starts later than usual is known as delayed puberty.
Notable among the morphologic changes in size, shape, composition, and functioning of the pubertal body, is the development of secondary sex characteristics, the "filling in" of the child's body; from girl to woman, from boy to man. Derived from the Latin puberatum (age of maturity), the word puberty describes the physical changes to sexual maturation, not the psychosocial and cultural maturation denoted by the term adolescent development in Western culture, wherein adolescence is the period of mental transition from childhood to adulthood, which overlaps much of the body's period of puberty.[12]
Differences between male and female puberty
Two of the most significant differences between puberty in females and puberty in males are the age at which it begins, and the major
.Although there is a wide range of normal ages, females typically begin puberty around ages 10–11 and end puberty around 15–17; males begin around ages 11–12 and end around 16–17.[1][2][3] Females attain reproductive maturity about four years after the first physical changes of puberty appear.[13] In contrast, males accelerate more slowly but continue to grow for about six years after the first visible pubertal changes.[14] Any increase in height beyond the post-pubertal age is uncommon.
For males, the
The hormonal maturation of females is considerably more complicated than in males. The main
Puberty onset
Puberty is preceded by adrenarche, marking an increase of adrenal androgen production between ages 6–10. Adrenarche is sometimes accompanied by the early appearance of axillary and pubic hair. The first androgenic hair resulting from adrenarche can be also transient and disappear before the onset of true puberty.
The onset of puberty is associated with high
The cause of the GnRH rise is unknown. Leptin might be the cause of the GnRH rise. Leptin has receptors in the hypothalamus which synthesizes GnRH.[20] Individuals who are deficient in leptin fail to initiate puberty.[21] The levels of leptin increase with the onset of puberty, and then decline to adult levels when puberty is completed. The rise in GnRH might also be caused by genetics. A study[22] discovered that a mutation in genes encoding both neurokinin B as well as the neurokinin B receptor can alter the timing of puberty. The researchers hypothesized that neurokinin B might play a role in regulating the secretion of kisspeptin, a compound responsible for triggering direct release of GnRH as well as indirect release of LH and FSH.
Effects of early and late puberty onset
Several studies about puberty have examined the effects of an early or a late onset of puberty in males and females. In general, females who enter puberty late experience positive outcomes in adolescence and adulthood, while females who enter puberty early experience negative outcomes. Males who have earlier pubertal timing generally have more positive outcomes in adulthood but more negative outcomes in adolescence, while the reverse is true for later pubertal timing.[23]
Females
Outcomes have generally indicated that early onset of puberty in females can be psychologically damaging. The main reason for this detrimental effect is the issue of body image. As they physically develop, gaining weight in several areas of the body, early-maturing females usually look larger than females who have not yet entered puberty. A result of the social pressure to be thin, the early-maturing females develop a negative view of their body image. In addition, people may tease the females about their visible breasts, forcing the early-maturing female to hide her breasts by dressing differently. Embarrassment about a more developed body may also result in the refusal to undress for gym. These experiences lead to lower self-esteem, more depression and poorer body image in these early-maturing females.[23]
Furthermore, as physical and emotional differences set them apart from people in their same age group, early-maturing females develop relationships with older people. For instance, some early-maturing females have older malefriends, "attracted to the females' womanly physique and femaleish innocence."[23] While having an older malefriend might improve popularity among peers, it also increases the risk of alcohol and drug use, increased sexual relations (often unprotected), eating disorders and bullying.[23]
Generally, later onset of puberty in females produces positive outcomes. They exhibit positive behaviors in adolescence that continue to adulthood.[23]
Males
In the past, early onset of puberty in males has been associated with positive outcomes, such as leadership in high school and success in adulthood.[24] However, recent studies have revealed that the risks and problems of early maturation in males might outweigh the benefits.[23]
Early-maturing males develop "more aggressive, law-breaking, and alcohol abusing" behaviors, which result in anger towards parents and trouble in school and with the police. Early puberty also correlates with increased sexual activity and a higher instance of teenage pregnancy, both of which can lead to depression and other psychosocial issues.[23] However, early puberty might also result in positive outcomes, such as popularity among peers, higher self-esteem and confidence, as a result of physical developments, such as taller height, developed muscles, muscular male breast and better athletic ability.
On the other hand, late-maturing males develop lower self-esteem and confidence and generally have lower popularity among peers, due to their less-developed physiques. Also, they experience problems with anxiety and depression and are more likely to be afraid of sex than other males.[23]
Changes in males
This section needs additional citations for verification. (October 2009) |
In males, puberty begins with the enlargement of the testicles and scrotum. The penis also increases in size, and a male develops pubic hair. A male's testicles also begin making sperm. The release of semen, which contains sperm and other fluids, is called ejaculation.[25] During puberty, a male's erect penis becomes capable of ejaculating semen and impregnating a female.[26][27] A male's first ejaculation is an important milestone in his development.[28] On average, a male's first ejaculation occurs at age 13.[4] Ejaculation sometimes occurs during sleep; this phenomenon is known as a nocturnal emission.[25]
Testicular size
In males, testicular enlargement is the first physical manifestation of puberty (and is termed
Male musculature and body shape
By the end of puberty, adult men have heavier bones and nearly twice as much skeletal muscle. Some of the bone growth (e.g. shoulder width and jaw) is disproportionately greater, resulting in noticeably different male and female skeletal shapes. The average adult male has about 150% of the lean body mass of an average female, and about 50% of the body fat.
This muscle develops mainly during the later stages of puberty, and muscle growth can continue even after males are biologically adult. The peak of the so-called "strength spurt", the rate of muscle growth, is attained about one year after a male experiences his peak growth rate.
Often, the fat pads of the male breast tissue and the male nipples will develop during puberty; sometimes, especially in one breast, this becomes more apparent and is termed gynecomastia. It is usually not a permanent phenomenon.
Erections
Foreskin retraction
During puberty, if not before, the tip and opening of a male's foreskin becomes wider, progressively allowing for retraction down the shaft of the penis and behind the glans, which ultimately should be possible without pain or difficulty. The membrane that bonds the inner surface of the foreskin with the glans disintegrates and releases the foreskin to separate from the glans. The foreskin then gradually becomes retractable.[39]
Research by Øster (1968) found that with the onset and continuation of puberty, the proportion of males able to pull back their foreskins increased. At ages 12–13, Øster found that only 60% of males were able to retract their foreskins; this increased to 85% by ages 14–15, and 95% by 16–17. He also found that 1% of those unable to fully retract experienced phimosis at ages 14–17, the remainder were partially able to.[39] The findings were supported by further research by Kayaba et al (1996) on a sample of over 600 males,[40] and Ishikawa and Kawakita (2004) found that by age 15, 77% of their sample of males could retract their foreskins.[41] Beaugé (1997) reports that males may assist the development of retractile foreskin by manual stretching.[42]
Once a male is able to retract his foreskin, penile hygiene should become an important feature of his routine body care. Although the American Academy of Pediatrics states there is "little evidence to affirm the association between circumcision status and optimal penile hygiene",[43] various studies suggest that males be educated about the role of hygiene, including retracting the foreskin while urinating and rinsing under it and around the glans at each bathing opportunity. Regular washing under the foreskin was found by Krueger and Osborn (1986) to reduce the risk of numerous penile disorders,[44] however Birley et al. (1993) report excessive washing with soap should be avoided because it dries the oils out of the tissues and can cause non-specific dermatitis.[45]
Pubic hair
Pubic hair often appears on a male shortly after the genitalia begin to grow. The pubic hairs are usually first visible at the dorsal (abdominal) base of the penis. The first few hairs are described as stage 2. Stage 3 is usually reached within another 6–12 months, when the hairs are too many to count. By stage 4, the pubic hairs densely fill the "pubic triangle". Stage 5 refers to the spread of pubic hair to the thighs and upward towards the navel as part of the developing abdominal hair.
Body and facial hair
In the months and years following the appearance of pubic hair, other areas of skin that respond to androgens may develop
Voice change and Adam's apple
Under the influence of androgens, the
Changes in females
Breast development
The first physical sign of puberty in females is usually a firm, tender lump under the center of the
Pubic hair
Vagina, uterus, ovaries
Before puberty, uterine body to cervix ratio is 1:1; which increases to 2:1 or 3:1 after completion of pubertal period.Menstruation and fertility
The first menstrual bleeding is referred to as menarche, and typically occurs about two years after thelarche.[52] The average age of menarche is 12.5 in the United States.[57] Most American females experience their first period at 11, 12 or 13, but some experience it earlier than their 11th birthday and others after their 14th birthday. In fact, anytime between 8 and 16 is normal. In Canada, the average age of menarche is 12.72,[58] and in the United Kingdom it is 12.9.[59] The time between menstrual periods (menses) is not always regular in the first two years after menarche.[60] Ovulation is necessary for fertility, but may or may not accompany the earliest menses.[61] In postmenarchal females, about 80% of the cycles were anovulatory in the first year after menarche, 50% in the third year and 10% in the sixth year.[60] Initiation of ovulation after menarche is not inevitable. A high proportion of females with continued irregularity in the menstrual cycle several years from menarche will continue to have prolonged irregularity and anovulation, and are at higher risk for reduced fertility.[62]
Body shape, fat distribution, and body composition
During this period, also in response to rising levels of estrogen, the lower half of the
Body odor and acne
Rising levels of
Visual and other effects of hormonal changes
In females,
Estradiol is also responsible for the increased production of
Testosterone will cause an enlargement of the
Changes of the vulva initiated by estradiol as well as its direct effects also appear to influence the functioning of the lower urinary tract.[67][68]
Underarm hair
Hair growth develops under the arms, starting out sparse before thickening and darkening over time.[69]
Variations
This section needs additional citations for verification. (May 2008) |
In a general sense, the conclusion of puberty is reproductive maturity. Criteria for defining the conclusion may differ for different purposes: attainment of the ability to reproduce, achievement of maximal adult height, maximal gonadal size, or adult sex hormone levels. Maximal adult height is achieved at an average age of 15 years for an average female and 18 years for an average male. Potential fertility (sometimes termed nubility) usually precedes completion of growth by 1–2 years in females and 3–4 years in males. Stage 5 typically represents maximal gonadal growth and adult hormone levels.
Age of onset
The definition of the onset of puberty may depend on perspective (e.g., hormonal versus physical) and purpose (establishing population normal standards, clinical care of early or late pubescent individuals, etc.). A common definition for the onset of puberty is physical changes to a person's body.[13] These physical changes are the first visible signs of neural, hormonal, and gonadal function changes.
The age at which puberty begins varies between individuals; usually, puberty begins between 10 and 13 years of age. The age at which puberty begins is affected by both genetic factors and by environmental factors such as nutritional state and social circumstances.[70] An example of social circumstances is the Vandenbergh effect; a juvenile female who has significant interaction with adult males will enter puberty earlier than juvenile females who are not socially overexposed to adult males.[71]
The average age at which puberty begins may be affected by ethnicity as well. For example, the average age of menarche in various populations surveyed has ranged from 12[57][58][59] to 18 years. The earliest average onset of puberty is for African-American females and the latest average onset for high altitude subsistence populations in Asia. However, much of the higher age averages reflect nutritional limitations more than genetic differences and can change within a few generations with a substantial change in diet. The median age of menarche for a population may be an index of the proportion of undernourished females in the population, and the width of the spread may reflect unevenness of wealth and food distribution in a population.
Researchers have identified an earlier age of the onset of puberty. However, they have based their conclusions on a comparison of data from 1999 with data from 1969. In the earlier example, the sample population was based on a small sample of white females (200, from Britain). The later study identified as puberty as occurring in 48% of African-American females by age nine, and 12% of white females by that age.[72]
One possible cause of a delay in the onset of puberty past the age 14 in females and 15 in males is
Historical shift
This section appears to contradict the article Menarche. (April 2021) |
The average age at which the onset of puberty occurs has dropped significantly since the 1840s.[75][76][77] In every decade from 1840 to 1950 there was a drop of four months in the average age of menarche among Western European females. In Norway, females born in 1840 had their menarche at an average age of 17 years. In France, the average in 1840 was 15.3 years. In England, the average in 1840 was 16.5 years. In Japan, the decline happened later and was then more rapid: from 1945 to 1975 in Japan there was a drop of 11 months per decade.
A 2006 study in Denmark found that puberty, as evidenced by breast development, started at an average age of 9 years and 10 months, a year earlier than when a similar study was done in 1991. Scientists believe the phenomenon could be linked to obesity or exposure to chemicals in the food chain, and is putting females at greater long-term risk of breast cancer.[78]
Genetic influence and environmental factors
Various studies have found direct genetic effects to account for at least 46% of the variation of timing of puberty in well-nourished populations.[79][80][81][82] The genetic association of timing is strongest between mothers and daughters. The specific genes affecting timing are not yet known.[79] Among the candidates is an androgen receptor gene.[83]
Researchers have hypothesized that early puberty onset may be caused by certain hair care products containing estrogen or placenta, and by certain chemicals, namely
If genetic factors account for half of the variation of pubertal timing, environment factors are clearly important as well. One of the first observed environmental effects is that puberty occurs later in children raised at higher altitudes. The most important of the environmental influences is clearly nutrition, but a number of others have been identified, all which affect timing of female puberty and menarche more clearly than male puberty.
Hormones and steroids
There is theoretical concern, and animal evidence, that environmental hormones and
Harder to detect as an influence on puberty are the more diffusely distributed environmental chemicals like PCBs (polychlorinated biphenyl), which can bind and trigger estrogen receptors.
More obvious degrees of partial puberty from direct exposure of young children to small but significant amounts of pharmaceutical sex steroids from exposure at home may be detected during medical evaluation for precocious puberty, but mild effects and the other potential exposures outlined above would not.
Nutritional influence
Much evidence suggests that for most of the last few centuries, nutritional differences accounted for majority of variation of pubertal timing in different populations, and even among social classes in the same population. Recent worldwide increased consumption of animal protein, other changes in nutrition, and increases in childhood obesity have resulted in falling ages of puberty, mainly in those populations with the higher previous ages. In many populations the amount of variation attributable to nutrition is shrinking.
Although available dietary energy (simple calories) is the most important dietary influence on timing of puberty, quality of the diet plays a role as well. Lower protein intakes and higher dietary fiber intakes, as occur with typical vegetarian diets, are associated with later onset and slower progression of female puberty.
Obesity influence and exercise
Scientific researchers have linked early obesity with an earlier onset of puberty in females. They have cited obesity as a cause of breast development before nine years and menarche before twelve years.[86] Early puberty in females can be a harbinger of later health problems.[87]
The average level of daily physical activity has also been shown to affect timing of puberty, especially in females. A high level of exercise, whether for athletic or body image purposes, or for daily subsistence, reduces energy calories available for reproduction and slows puberty. The exercise effect is often amplified by a lower body fat mass and cholesterol.
Physical and mental illness
Chronic diseases can delay puberty in both males and females. Those that involve chronic inflammation or interfere with nutrition have the strongest effect. In the western world,
Mental illnesses occur in puberty. The brain undergoes significant development by hormones which can contribute to mood disorders such as major depressive disorder, bipolar disorder, dysthymia and schizophrenia. Females aged between 15 and 19 make up 40% of anorexia nervosa cases.[88]
Stress and social factors
Some of the least understood environmental influences on timing of puberty are social and psychological. In comparison with the effects of genetics, nutrition, and general health, social influences are small, shifting timing by a few months rather than years. Mechanisms of these social effects are unknown, though a variety of physiological processes, including pheromones, have been suggested based on animal research.
The most important part of a child's psychosocial environment is the family, and most of the social influence research has investigated features of family structure and function in relation to earlier or later female puberty. Most of the studies have reported that menarche may occur a few months earlier in females in high-stress households, whose fathers are absent during their early childhood, who have a stepfather in the home, who are subjected to prolonged sexual abuse in childhood, or who are adopted from a developing country at a young age. Conversely, menarche may be slightly later when a female grows up in a large family with a biological father present.
More extreme degrees of environmental stress, such as wartime refugee status with threat to physical survival, have been found to be associated with delay of maturation, an effect that may be compounded by dietary inadequacy.
Most of these reported social effects are small and our understanding is incomplete. Most of these "effects" are statistical associations revealed by epidemiologic surveys. Statistical associations are not necessarily causal, and a variety of covariables and alternative explanations can be imagined. Effects of such small size can never be confirmed or refuted for any individual child. Furthermore, interpretations of the data are politically controversial because of the ease with which this type of research can be used for political advocacy. Accusations of bias based on political agenda sometimes accompany scientific criticism.
Another limitation of the social research is that nearly all of it has concerned females, partly because female puberty requires greater physiologic resources and partly because it involves a unique event (menarche) that makes survey research into female puberty much simpler than male. More detail is provided in the menarche article.
Variations of sequence
The sequence of events of pubertal development can occasionally vary. For example, in about 15% of males and females, pubarche (the first pubic hairs) can precede, respectively, gonadarche and thelarche by a few months. Rarely, menarche can occur before other signs of puberty in a few females. These variations deserve medical evaluation because they can occasionally signal a disease.
Neurohormonal process
The endocrine
- The brain's GnRH.
- Cells in the FSHinto the circulation.
- The testes respond to the rising amounts of LH and FSH by growing and beginning to produce estradiol and testosterone.
- Rising levels of estradiol and testosterone produce the body changes of female and male puberty.
The onset of this neurohormonal process may precede the first visible body changes by 1–2 years.
Components of the endocrine reproductive system
The
The pituitary gland responds to the pulsed GnRH signals by releasing LH and FSH into the blood of the general circulation, also in a pulsatile pattern.
The gonads (
The adrenal glands are a second source for steroid hormones. Adrenal maturation, termed adrenarche, typically precedes gonadarche in mid-childhood.
Major hormones
- tachykinin peptide) and kisspeptin (a neuropeptide), both present in KNDy neurons of the hypothalamus, are critical parts of the control system that switches on the release of GnRH at the start of puberty.[89]
- gonadotrope cells of the anterior pituitary.
- theca cells of the ovaries. LH secretion changes more dramatically with the initiation of puberty than FSH, as LH levels increase about 25-fold with the onset of puberty, compared with the 2.5-fold increase of FSH.
- gonadotrope cells of the anterior pituitary. The main target cells of FSH are the ovarian follicles and the Sertoli cells and spermatogenic tissue of the testes.
- theca cells of the ovaries and the adrenal cortex. Testosterone is the primary mammalian androgen and the "original" anabolic steroid. It acts on androgen receptorsin responsive tissue throughout the body.
- Estradiol is a steroid hormone produced by aromatization of testosterone. Estradiol is the principal human estrogen and acts on estrogen receptors throughout the body. The largest amounts of estradiol are produced by the granulosa cells of the ovaries, but lesser amounts are derived from testicular and adrenal testosterone.
- zona reticulosa of the adrenal cortex in both sexes. The major adrenal androgens are dehydroepiandrosterone, androstenedione (which are precursors of testosterone), and dehydroepiandrosterone sulfate which is present in large amounts in the blood. Adrenal androgens contribute to the androgenic events of early puberty in females.
- IGF1 (insulin-like growth factor 1) rises substantially during puberty in response to rising levels of growth hormone and may be the principal mediator of the pubertal growth spurt.
- energy metabolism. It also plays a permissive role in female puberty, which usually will not proceed until an adequate body mass has been achieved.
Endocrine perspective
The
Normal puberty is initiated in the hypothalamus, with de-inhibition of the pulse generator in the arcuate nucleus. This inhibition of the arcuate nucleus is an ongoing active suppression by other areas of the brain. The signal and mechanism releasing the arcuate nucleus from inhibition have been the subject of investigation for decades and remain incompletely understood. Leptin levels rise throughout childhood and play a part in allowing the arcuate nucleus to resume operation. If the childhood inhibition of the arcuate nucleus is interrupted prematurely by injury to the brain, it may resume pulsatile gonadotropin release and puberty will begin at an early age.
Neurons of the arcuate nucleus secrete
Some investigators have attributed the onset of puberty to a resonance of oscillators in the brain.[93][94][95] By this mechanism, the gonadotropin pulses that occur primarily at night just before puberty represent beats.[96][97][98][99]
An array of "autoamplification processes" increases the production of all of the pubertal hormones of the hypothalamus, pituitary, and gonads.[100]
Regulation of adrenarche and its relationship to maturation of the hypothalamic-gonadal axis is not fully understood, and some evidence suggests it is a parallel but largely independent process coincident with or even preceding central puberty. Rising levels of adrenal androgens (termed adrenarche) can usually be detected between 6 and 11 years of age, even before the increasing gonadotropin pulses of hypothalamic puberty. Adrenal androgens contribute to the development of pubic hair (pubarche), adult body odor, and other androgenic changes in both sexes. The primary clinical significance of the distinction between adrenarche and gonadarche is that pubic hair and body odor changes by themselves do not prove that central puberty is underway for an individual child.
Hormonal changes in males
Early stages of male hypothalamic maturation seem to be very similar to the early stages of female puberty, though occurring about 1–2 years later.
LH stimulates the Leydig cells of the testes to make testosterone and blood levels begin to rise. For much of puberty, nighttime levels of testosterone are higher than daytime. Regularity of frequency and amplitude of gonadotropin pulses seems to be less necessary for progression of male than female puberty.
However, a significant portion of
Another hormonal change in males takes place during the teenage years for most young men. At this point in a male's life the testosterone levels slowly rise, and most of the effects are mediated through the androgen receptors by way of conversion dihydrotestosterone in target organs (especially that of the bowels).
Hormonal changes in females
As the amplitude of LH pulses increases, the theca cells of the ovaries begin to produce testosterone and smaller amounts of
Rising levels of estradiol produce the characteristic estrogenic body changes of female puberty: growth spurt, acceleration of bone maturation and closure,
As the estradiol levels gradually rise and the other autoamplification processes occur, a point of maturation is reached when the feedback sensitivity of the hypothalamic "gonadostat" becomes positive. This attainment of positive feedback is the hallmark of female sexual maturity, as it allows the mid cycle
Growth hormone levels rise steadily throughout puberty.
Hormone | Units | Prepubertal Stage 1 |
Stage 2 | Stage 3 | Stage 4 | Stage 5 | |
---|---|---|---|---|---|---|---|
Phase | |||||||
LH | mIU/mL | 2.7 (<1.0–5.5) | 4.2 (<1.0–9.0) | 6.7 (<1.0–14.6) | 7.7 (2.8–15.0) | Follicular Luteal |
7.6 (3–18) 6.6 (3–18) |
U/L | <0.1 (<0.1–0.2) | 0.7 (<0.1–2.8) | 2.1 (<0.1–6.8) | 3.6 (0.9–8.1) | Follicular Luteal |
3.8 (1.6–8.1) 3.5 (1.5–8.0) | |
FSH | mIU/mL | 4.0 (<1–5) | 4.6 (<1.0–7.2) | 6.8 (3.3–10.5) | 7.4 (3.3–10.5) | Follicular Luteal |
10.3 (6–15) 6.0 (3.4–8.6) |
U/L | 2.1 (<0.5–5.4) | 3.5 (<0.5–6.6) | 4.9 (0.7–9.0) | 6.2 (1.1–11.3) | Follicular Luteal |
6.6 (1.9–10.8) 5.4 (1.8–10.5) | |
Estradiol | pg/mL | 9 (<9–20) | 15 (<9–30) | 27 (<9–60) | 55 (16–85) | Follicular Luteal |
50 (30–100) 130 (70–300) |
Estrone | pg/mL | 13 (<9–23) | 18 (10–37) | 26 (17–58) | 36 (23–69) | Follicular Luteal |
44 (30–89) 75 (39–160) |
Progesterone | ng/dL | 22 (<10–32) | 30 (10–51) | 36 (10–75) | 175 (<10–2500) | Follicular Luteal |
35 (13–75) (200–2500) |
Hydroxyprogesterone
|
ng/dL | 33 (<10–84) | 52 (10–98) | 75 (10–185) | 97 (17–235) | Follicular Luteal |
48 (12–90) 178 (35–290) |
DHEA-S | µg/dL | 49a (20–95) 106b (40–200) |
129 (60–240) | 155 (85–290) | 195 (106–320) | – | 220 (118–320) |
DHEA | ng/dL | 35a (<10–70) 127b (72–180) |
297 (150–540) | 328 (190–620) | 394 (240–768) | – | 538 (215–855) |
Androstenedione | ng/dL | 26 (<10–50) | 77 (40–112) | 126 (55–190) | 147 (70–245) | – | 172 (74–284) |
Testosterone | ng/dL | 10 (<10–22) | 18 (<10–29) | 26 (<10–40) | 38 (24–62) | – | 40 (27–70) |
Notes: Values are mean plasma levels, with ranges in parentheses. a = Pre-adrenarche. b = Post-adrenarche. ( adrenal androgen section, occurs as a separate event and can precede puberty onset by 1 to 2 years.) Sources: [101]
|
Stages
- adrenarche (approximately age 11)
- gonadarche (approximately age 8)
- thelarche (approximately age 11 in females)
- pubarche (approximately age 12)
- menarche (approximately age 12.5 in females)
- spermarche (approximately age 13.5 in males[102])
See also
References
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The changes that occur during puberty usually happen in an ordered sequence, beginning with thelarche (breast development) at around age 10 or 11, followed by adrenarche (growth of pubic hair due to androgen stimulation), peak height velocity, and finally menarche (the onset of menses), which usually occurs around age 12 or 13.
- ^ ISBN 978-1-4833-6475-9.
On average, the onset of puberty is about 18 months earlier for girls (usually starting around the age of 10 or 11 and lasting until they are 15 to 17) than for boys (who usually begin puberty at about the age of 11 to 12 and complete it by the age of 16 to 17, on average).
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Sources
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- Gungor N, Arslanian SA (2002). "Chapter 21: Nutritional disorders: integration of energy metabolism and its disorders in childhood". In Sperling MA (ed.). Pediatric Endocrinology (2nd ed.). Philadelphia: Saunders. pp. 689–724. ISBN 978-0-7216-9539-6.
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- Rosenfield RL (2002). "Chapter 16: Female puberty and its disorders". In Sperling, MA (ed.). Pediatric Endocrinology (2nd ed.). Philadelphia: Saunders. pp. 455–518. ISBN 978-0-7216-9539-6.
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Further reading
- Colburn, T., Dumanoski, D. and Myers, J.P. Our Stolen Future, 1996, Plume: New York.
- Ducros, A. and Pasquet, P. "Evolution de l'âge d'apparition des premières règles (ménarche) en France". Biométrie Humaine (1978), 13, 35–43.
- Gluckman PD, Hanson MA (2006). "Evolution, development and timing of puberty". Trends in Endocrinology and Metabolism. 17 (1): 7–12. S2CID 26141301.
- Herman-Giddens ME, Slora EJ, Wasserman RC, Bourdony CJ, Bhapkar MV, Koch GG, et al. (1997). "Secondary sexual characteristics and menses in young girls seen in office practice: a study from the Pediatric Research in Office Settings network". Pediatrics. 99 (4): 505–12. PMID 9093289. Newer data suggesting that lower age thresholds for evaluation should be used.
- Plant TM, Lee PA, eds. The Neurobiology of Puberty. Bristol: Society for Endocrinology, 1995. Proceedings of the latest (4th) International Conference on the Control of the Onset of Puberty, containing summaries of current theories of physiological control, as well as GnRH analog treatment.
- Sizonenko, PC. Role of sex steroids during development—integration Archived 2013-07-04 at the ISBN 0-444-50296-3. pp 299–306.
- Tanner JM, Davies PS (1985). "Clinical longitudinal standards for height and height velocity for North American children". The Journal of Pediatrics. 107 (3): 317–29. PMID 3875704. Highly useful growth charts with integrated standards for stages of puberty.
- Terasawa E, Fernandez DL (2001). "Neurobiological mechanisms of the onset of puberty in primates". Endocrine Reviews. 22 (1): 111–51. PMID 11159818.
- "Research shows how evolution explains age of puberty", ScienceDaily, December 1, 2005
External links
- Support for teens (archive)
- University of Maryland guide to puberty and adolescence
- Growing Up Sexually: A World Atlas
- Pictures and detailed information about breast development during puberty
- Puberty in females: interactive animation of Tanner stages
- Puberty in males: interactive animation of Tanner stages