Thelarche, also known as breast budding, is the onset of secondary breast development, often representing the beginning of pubertal development. [1] It is the stage at which male and female breasts differentiate due to variance in hormone levels; however, some males have a condition in which they develop breasts, termed gynecomastia. [2] [3] Thelarche typically occurs between the ages of 8 and 13 years with significant variation between individuals. [4] [5] [1] However, the initial growth of breast tissue occurs during fetal development.
Usually, females experience menarche about two years after thelarche has begun, with complete breast development from thelarche to adult breasts, taking between 2 and 4 years but can be up to 18. [1] [6] Moreover, puberty is considered delayed if breast development does not start at age 13 or if a female has not had her first period (menarche) within three years of thelarche. [7] Additionally, secondary breast development occurring before the age of 7 years could be a sign of premature thelarche or precocious puberty. Of note, for some girls, thelarche will occur, with subsequent regression of breast development, and then months or years later, normal breast growth will commence again accompanied by normal pubertal changes; this is termed transient thelarche. [1]
Pubertal changes, including breast development, are assessed using the Tanner Scale (Sexual Maturity Rating Scale) where stage 1 is before, stage 2 is the breast budding or thelarche stage, stages 3 and 4 are continual breast growth and areolar development, and stage 5 signifies completion of development. [6] [8] This system does not use breast size but instead examines the shape of breasts, nipples, and areolae to determine the progression of growth. [6]
Various hormones interact and result in the changes seen during thelarche. The growth and accumulation of adipose tissue in the breasts are induced by estrogen, while the development of mammary glands and areolae are caused by progesterone; both estrogen and progesterone are produced by ovaries. [1] [3] [6] Due to change in hormone levels, young breasts are likely to develop asymmetrically, and in many cases, adult breasts will remain unequal in size or shape. [4] [6]
The age of thelarche has been decreasing in the past few decades. Between 1973 and 2013, the age of thelarche decreased at a rate of 0.24 years per decade. [9] Other contemporary trends that may be contributing to this change in the onset of thelarche include increasing BMI, changes in pubertal timing, and environmental exposures. [9] [10] Studies also indicate associations between the average age of thelarche and race. [3] [5] The average age of thelarche for African American females in the United States is between 8.9 and 9.5 years, the average for Caucasians is 10–10.4 years, and the average age of thelarche for Hispanic females is approximately 9.8 years. [3] [5] Additionally, in African American and Mexican American girls, breast development may occur earlier than in other ethnic cohorts and can be normal in the 7th year of age. [11] Due to the decreasing age of thelarche over time, there is discussion of adjusting the cutoff for early thelarche to 7 years old for white females and six years old for black females. [12]
Furthermore, there have been associations between obesity, chemical contaminants, and the earlier average age of thelarche. Studies have shown that obesity is associated with an earlier average age of thelarche. [13] Moreover, the prevalence of premature thelarche has been increasing over the past several years which many attribute to pesticides. Experimental data indicate the impact of chemical contaminants in gestation and puberty, with the chemical such as phthalates having a high association with premature thelarche frequency. [14]
Premature thelarche is a benign condition in which a young female has breast development before age eight without any accompanied pubertal changes. [2] [7] [15] [16] Individuals undergoing isolated premature thelarche do not experience menstruation, pubic hair growth (pubarche), or the bone growth characteristic of puberty. [15] Initial breast development can be bilateral or unilateral and usually begins with a firm, disc-like area of tissue under the areola, which can be mistaken for a mass but is almost always a normal physiologic process. [1] The breast is often tender, and palpation is sometimes painful, but breast discharge is absent. [2] Usually, the breasts do not develop past stage 3 on the Tanner Scale, hence maintaining adolescent nipples. [4] [15] Moreover, in 90% of patients with isolated premature thelarche, breast enlargement will resolve six months to 6 years after diagnosis. [1]
The most common age for females to develop isolated premature thelarche is between 0 and 2 years, with a prevalence rate between 2.2 and 4.7 percent of all female infants. [7] [17] The breasts of these females typically exhibit alternating progression and regression patterns of growth in 6-week intervals, often completely decreasing in size within 1.5 years. [5] [4] [15] [18] Due to the benign nature of the condition and the tendency to self-resolve, premature thelarche does not require treatment. [18] However, premature thelarche should be evaluated to rule out additional causes, such as hypothyroidism or precocious puberty, especially if other symptoms are present. Such evaluations will typically involve serial examinations and radiographs. [1]
Precocious puberty is a condition where children undergo puberty before seven or eight years. [5] Precocious puberty differs from premature thelarche in that the individual experiences additional aspects of puberty, including menarche, adrenarche, pubarche, vaginal discharge, and bone growth, while the sole presence of early thelarche identifies premature thelarche. [12] Though premature thelarche and precocious puberty are distinct conditions, there is some overlap; an estimated 14 to 18 percent of females who exhibit premature thelarche will additionally develop precocious puberty. [1] [4] [5] Precocious puberty can be identified using a pelvic ultrasound to assess the size of ovaries and uterus relative to the individual's age. [5] Other methods of diagnosis consist of blood tests to determine hormone levels and simple physician assessments with follow-up appointments to track the progression of development. [5]
The thelarche variant, also named exaggerated thelarche, is an intermediate condition between premature thelarche and precocious puberty. [15] This condition resembles premature thelarche without the cyclic waxing and waning of breast growth. [15] Pubic hair growth (pubarche) and advanced bone growth are often present in the thelarche variant. Yet, this growth does not result in complete sexual maturity as occurs with precocious puberty. [15] [18]
Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic disorder in which a person's cells have only one X chromosome or are partially missing an X chromosome leading to the complete or partial deletion of the pseudoautosomal regions in the affected X chromosome. Most people have two sex chromosomes. The chromosomal abnormality is often present in just some cells, in which case it is known as Turner syndrome with mosaicism. 45,X0 with mosaicism can occur in males or females, but Turner syndrome without mosaicism only occurs in females. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low hairline at the back of the neck, short stature, and swollen hands and feet are seen at birth. Typically, those affected do not develop menstrual periods or breasts without hormone treatment and are unable to have children without reproductive technology. Heart defects, diabetes, and hypothyroidism occur in the disorder more frequently than average. Most people with Turner syndrome have normal intelligence; however, many have problems with spatial visualization that may be needed in order to learn mathematics. Vision and hearing problems also occur more often than average.
Menarche is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility.
Amenorrhea or amenorrhoea is the absence of a menstrual period in a female who has reached reproductive age. Physiological states of amenorrhoea are seen, most commonly, during pregnancy and lactation (breastfeeding). Outside the reproductive years, there is absence of menses during childhood and after menopause.
In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. There is early development of secondary sex characters and gametogenesis also starts earlier. Precocious puberty is of two types: true precocious puberty and pseudoprecocious puberty. In a minority of children with precocious puberty, the early development is triggered by a disease such as a tumor or injury of the brain.
Delayed puberty is when a person lacks or has incomplete development of specific sexual characteristics past the usual age of onset of puberty. The person may have no physical or hormonal signs that puberty has begun. In the United States, girls are considered to have delayed puberty if they lack breast development by age 13 or have not started menstruating by age 15. Boys are considered to have delayed puberty if they lack enlargement of the testicles by age 14. Delayed puberty affects about 2% of adolescents.
The Tanner scale is a scale of physical development as children transition into adolescence and then adulthood. The scale defines physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, genitals, testicular volume, and growth of pubic hair. This scale was first quantified in 1969 by James Tanner, a British pediatrician, after a two-decade-long study following the physical changes in girls undergoing puberty.
Adrenarche is an early stage in sexual maturation that happens in some higher primates, typically peaks at around 20 years of age, and is involved in the development of pubic hair, body odor, skin oiliness, axillary hair, sexual attraction/sexual desire/increased libido and mild acne. During adrenarche the adrenal glands secrete increased levels of weak adrenal androgens, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A4), but without increased cortisol levels. Adrenarche is the result of the development of a new zone of the adrenal cortex, the zona reticularis. Adrenarche is a process related to puberty, but distinct from hypothalamic–pituitary–gonadal axis maturation and function.
Pubarche refers to the first appearance of pubic hair at puberty and it also marks the beginning of puberty. It is one of the physical changes of puberty and can occur independently of complete puberty. The early stage of sexual maturation, also known as adrenarche, is marked by characteristics including the development of pubic hair, axillary hair, adult apocrine body odor, acne, and increased oiliness of hair and skin. The Encyclopedia of Child and Adolescent Health corresponds SMR2 with pubarche, defining it as the development of pubic hair that occurs at a mean age of 11.6 years in females and 12.6 years in males. It further describes that pubarche's physical manifestation is vellus hair over the labia or the base of the penis. See Table 1 for the entirety of the sexual maturity rating description.
Gonadarche refers to the earliest gonadal changes of puberty. In response to pituitary gonadotropins, the ovaries in females and the testes in males begin to grow and increase the production of the sex steroids, especially estradiol and testosterone. The ovary and testis have receptors, follicle cells and leydig cells, respectively, where gonadotropins bind to stimulate the maturation of the gonads and secretion of estrogen and testosterone. Certain disorders can result in changes to timing or nature of these processes.
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
Spermarche, also known as semenarche, is the time at which a male experiences their first ejaculation. It is considered to be the counterpart of menarche in females. Depending on upbringing, cultural differences, and prior sexual knowledge, males may have different reactions to spermarche, ranging from fear to excitement. Spermarche is one of the first events in the life of a male leading to sexual maturity. It occurs at the time when the secondary sex characteristics are just beginning to develop. Researchers have had difficulty determining the onset of spermarche because it is reliant on self-reporting. Other methods to determine it have included the examination of urine samples to determine the presence of spermatozoa. The presence of sperm in urine is referred to as spermaturia.
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes.
Aromatase excess syndrome is a rarely diagnosed genetic and endocrine syndrome which is characterized by an overexpression of aromatase, the enzyme responsible for the biosynthesis of the estrogen sex hormones from the androgens, in turn resulting in excessive levels of circulating estrogens and, accordingly, symptoms of hyperestrogenism. It affects both sexes, manifesting itself in males as marked or complete phenotypical feminization and in females as hyperfeminization.
Hypergonadotropic hypogonadism (HH), also known as primary or peripheral/gonadal hypogonadism or primary gonadal failure, is a condition which is characterized by hypogonadism which is due to an impaired response of the gonads to the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and in turn a lack of sex steroid production. As compensation and the lack of negative feedback, gonadotropin levels are elevated. Individuals with HH have an intact and functioning hypothalamus and pituitary glands so they are still able to produce FSH and LH. HH may present as either congenital or acquired, but the majority of cases are of the former nature. HH can be treated with hormone replacement therapy.
Gonadotropin-releasing hormone (GnRH) insensitivity also known as Isolated gonadotropin-releasing hormone (GnRH)deficiency (IGD) is a rare autosomal recessive genetic and endocrine syndrome which is characterized by inactivating mutations of the gonadotropin-releasing hormone receptor (GnRHR) and thus an insensitivity of the receptor to gonadotropin-releasing hormone (GnRH), resulting in a partial or complete loss of the ability of the gonads to synthesize the sex hormones. The condition manifests itself as isolated hypogonadotropic hypogonadism (IHH), presenting with symptoms such as delayed, reduced, or absent puberty, low or complete lack of libido, and infertility, and is the predominant cause of IHH when it does not present alongside anosmia.
Puberty blockers are medicines used to postpone puberty in children. The most commonly used puberty blockers are gonadotropin-releasing hormone (GnRH) agonists, which suppress the natural production of sex hormones, such as androgens and estrogens. Puberty blockers are used to delay puberty in children with precocious puberty. They are also used to delay the development of unwanted secondary sex characteristics in transgender children, so as to allow transgender youth more time to explore their gender identity. The same drugs are also used in fertility medicine and to treat some hormone-sensitive cancers in adults.
Gynecomastia is the abnormal non-cancerous enlargement of one or both breasts in males due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Gynecomastia can cause significant psychological distress or unease.
Pediatric gynaecology or pediatric gynecology is the medical practice dealing with the health of the vagina, vulva, uterus, and ovaries of infants, children, and adolescents. Its counterpart is pediatric andrology, which deals with medical issues specific to the penis and testes.
Premature thelarche (PT) is a medical condition, characterised by isolated breast development in female infants. It occurs in females younger than 8 years, with the highest occurrence before the age of 2. PT is rare, occurring in 2.2-4.7% of females aged 0 to 2 years old. The exact cause of the condition is still unknown, but it has been linked to a variety of genetic, dietary and physiological factors.
The medical uses of bicalutamide, a nonsteroidal antiandrogen (NSAA), include the treatment of androgen-dependent conditions and hormone therapy to block the effects of androgens. Indications for bicalutamide include the treatment of prostate cancer in men, skin and hair conditions such as acne, seborrhea, hirsutism, and pattern hair loss in women, high testosterone levels in women, hormone therapy in transgender women, as a puberty blocker to prevent puberty in transgender girls and to treat early puberty in boys, and the treatment of long-lasting erections in men. It may also have some value in the treatment of paraphilias and hypersexuality in men.
breast development stages.
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