If the cause can be traced to the hypothalamus or pituitary, the cause is considered central. Other names for this type are "complete" or "true precocious" puberty.

Causes of central precocious puberty can include:

- damage to the inhibitory system of the brain (due to infection, trauma, or irradiation),

- hypothalamic hamartoma produces pulsatile gonadotropin-releasing hormone (GnRH),

- Langerhans cell histiocytosis, or

- McCune–Albright syndrome.

Central precocious puberty can be caused by intracranial neoplasm, infection (most commonly central nervous system tuberculosis especially in developing countries), trauma, hydrocephalus, and Angelman syndrome. Precocious puberty is associated with advancement in bone age, which leads to early fusion of epiphyses, thus resulting in reduced final height and short stature.

Precocious puberty can make a child fertile when very young, with the youngest mother on record being Lina Medina, who gave birth at the age of 5 years, 7 months and 17 days, in one report and at 6 years 5 months in another.

"Central precocious puberty (CPP) was reported in some patients with suprasellar arachnoid cysts (SAC), and SCFE (slipped capital femoral epiphysis) occurs in patients with CPP because of rapid growth and changes of growth hormone secretion."

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

The deficiency causes the virilization of XX fetuses. Although they will have normal female internal genitalia, clitoromegaly often results from the high androgen levels in utero, along with ambiguous external genitalia upon birth.

Testosterone may be normal or elevated.

Later, the lack of estrogen results in the presentation of primary amenorrhea and tall stature. The taller than expected height occurs because estrogen normally causes fusion of the epiphyseal growth plates in the bones, and in its absence, the girl will keep growing longer. The gonadotropins LH and FSH will both be elevated and patients present with polycystic ovaries. Furthermore, the low estrogen will predispose those with the condition to osteoporosis.

Aromatase deficiency in the baby can also affect the mother during gestation, with cystic acne, hirsutism, deepening of the voice, and clitoromegaly. Increased circulating testosterone levels are the cause. The mother's symptoms resolve after she gives birth.

Examples of symptoms of hypogonadism with underdevelopment of the Gonads (testicles and ovaries) include delayed, reduced, or absent puberty, low libido, and infertility.

Secondary sexual development induced by sex steroids from other abnormal sources is referred to as "peripheral precocious puberty" or "precocious pseudopuberty." It typically presents as a severe form of disease with children. Symptoms are usually as a sequelae from adrenal insufficiency (because of 21-hydroxylase deficiency or 11-beta hydroxylase deficiency, the former being more common), which includes but is not limited to hypertension, hypotension, electrolyte abnormalities, ambiguous genitalia in females, signs of virilization in females. Blood tests will typically reveal high level of androgens with low levels of cortisol.

Causes can include:

- Endogenous sources

- gonadal tumors (such as arrhenoblastoma),

- adrenal tumors,

- germ cell tumor,

- congenital adrenal hyperplasia,

- McCune–Albright syndrome,

- Exogenous hormones

- Environmental exogenous hormones,

- As treatment for another condition.

Children who are healthy but have a slower rate of physical development than average have constitutional delay of growth and puberty. These children have a history of stature shorter than their age-matched peers throughout childhood, but their height is appropriate for bone age, and skeletal development is delayed more than 2.5 SD. They usually are thin and often have a family history of delayed puberty. Children with a combination of a family tendency toward short stature and constitutional delay of growth and puberty are the most likely to seek evaluation. They quite often seek evaluation when classmates or friends undergo pubertal development and growth, thereby accentuating their delay.

It is often difficult to establish if it is a true constitutional delay of growth and puberty or if there is an underlying pathology, because biochemical tests are not always discriminatory. Short stature, delayed growth in height and weight, and/or delayed puberty may be the only clinical manifestations of coeliac disease, in absence of any other symptoms.

Examples of symptoms of hypogonadism include delayed, reduced, or absent puberty, low libido, and infertility.

FSH insensitivity presents itself in females as two clusters of symptoms: 1) hypergonadotropic hypogonadism or hypoestrogenism, resulting in a delayed, reduced, or fully absent puberty and associated sexual infantilism (if left untreated), reduced uterine volume, and osteoporosis; and 2) ovarian dysgenesis or failure, resulting in primary or secondary amenorrhea, infertility, and normal sized to slightly enlarged ovaries. Males on the other hand are significantly less affected, presenting merely with partial or complete infertility, reduced testicular volume, and oligozoospermia (reduced spermatogenesis).

Hypogonadotropic hypogonadism (HH), also known as secondary or central hypogonadism, as well as gonadotropin-releasing hormone deficiency or gonadotropin deficiency (GD), is a condition which is characterized by hypogonadism due to an impaired secretion of gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH), by the pituitary gland in the brain, and in turn decreased gonadotropin levels and a resultant lack of sex steroid production.

Follicle-stimulating hormone (FSH) insensitivity, or ovarian insensitivity to FSH in females, also referable to as ovarian follicle hypoplasia or granulosa cell hypoplasia in females, is a rare autosomal recessive genetic and endocrine syndrome affecting both females and males, with the former presenting with much greater severity of symptomatology. It is characterized by a resistance or complete insensitivity to the effects of follicle-stimulating hormone (FSH), a gonadotropin which is normally responsible for the stimulation of estrogen production by the ovaries in females and maintenance of fertility in both sexes. The condition manifests itself as hypergonadotropic hypogonadism (decreased or lack of production of sex steroids by the gonads despite high circulating levels of gonadotropins), reduced or absent puberty (lack of development of secondary sexual characteristics, resulting in sexual infantilism if left untreated), amenorrhea (lack of menstruation), and infertility in females, whereas males present merely with varying degrees of infertility and associated symptoms (e.g., decreased sperm production).

A related condition is luteinizing hormone (LH) insensitivity (termed Leydig cell hypoplasia when it occurs in males), which presents with similar symptoms to those of FSH insensitivity but with the symptoms in the respective sexes reversed (i.e., hypogonadism and sexual infantilism in males and merely problems with fertility in females); however, males also present with feminized or ambiguous genitalia (also known as pseudohermaphroditism), whereas ambiguous genitalia does not occur in females with FSH insensitivity. Despite their similar causes, LH insensitivity is considerably more common in comparison to FSH insensitivity.

Approximate mean ages for the onset of various pubertal changes are as follows. Ages in parentheses are the approximate 3rd and 97th percentiles for attainment. For example, less than 3% of girls have not yet achieved thelarche by 13 years of age. Developmental changes during puberty in girls occur over a period of 3 – 5 years, usually between 10 and 15 years of age. They include the occurrence of secondary characteristics beginning with breast development, the adolescent growth spurt, the onset of menarche – which does not correspond to the end of puberty – and the acquisition of fertility, as well as profound psychological modifications.

The normal variation in the age at which adolescent changes occur is so wide that puberty cannot be considered to be pathologically delayed until the menarche has failed to occur by the age of 18 or testicular development by the age of 20.

The sources of the data, and a fuller description of normal timing and sequence of pubertal events, as well as the hormonal changes that drive them, are provided in the principal article on puberty. It is worthwhile to consider the world geographical and ethnographic/demographic limits and deficits of this study.

Hypergonadotropic hypogonadism (HH), also known as primary or peripheral/gonadal hypogonadism, is a condition which is characterized by hypogonadism 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 and elevated gonadotropin levels (as an attempt of compensation by the body). HH may present as either "congenital" or "acquired", but the majority of cases are of the former nature.

Familial male-limited precocious puberty, often abbreviated as FMPP, also known as familial sexual precocity or gonadotropin-independent testotoxicosis, is a form of gonadotropin-independent precocious puberty in which boys experience early onset and progression of puberty. Signs of puberty can develop as early as an age of 1 year.

The spinal length in boys may be short due to a rapid advance in epiphyseal maturation. It is an autosomal dominant condition with a mutation of the luteinizing hormone (LH) receptor. Treatment is with drugs that suppress gonadal steroidogenesis, such as cyproterone acetate, ketoconazole, spironolactone, and testolactone. Alternatively, the combination of the androgen receptor antagonist bicalutamide and the aromatase inhibitor anastrozole may be used.

Observed physiological abnormalities of the condition include a dramatic overexpression of aromatase and, accordingly, excessive levels of estrogens including estrone and estradiol and a very high rate of peripheral conversion of androgens to estrogens. In one study, cellular aromatase mRNA expression was found to be at least 10 times higher in a female patient compared to the control, and the estradiol/testosterone ratio after an injection of testosterone in a male patient was found to be 100 times greater than the control. Additionally, in another study, androstenedione, testosterone, and dihydrotestosterone (DHT) were found to be either low or normal in males, and follicle-stimulating hormone (FSH) levels were very low (likely due to suppression by estrogen, which has antigonadotropic effects as a form of negative feedback inhibition on sex steroid production in sufficiently high amounts), whereas luteinizing hormone (LH) levels were normal.

According to a recent review, estrone levels have been elevated in 17 of 18 patients (94%), while estradiol levels have been elevated only in 13 of 27 patients (48%). As such, estrone is the main estrogen elevated in the condition. In more than half of patients, circulating androstenedione and testosterone levels are low to subnormal. The ratio of circulating estradiol to testosterone is >10 in 75% of cases. FSH levels are said to be consistently low in the condition, while LH levels are in the low to normal range.

It is notable that gynecomastia has been observed in patients in whom estradiol levels are within the normal range. This has been suggested to be due to "in situ" conversion of adrenal androgens into estrone and then estradiol (via local 17β-HSD) in breast tissue (where aromatase activity may be particularly high).

The symptoms of AES, in males, include heterosexual precocity (precocious puberty with phenotypically-inappropriate secondary sexual characteristics; i.e., a fully or mostly feminized appearance), severe prepubertal or peripubertal gynecomastia (development of breasts in males before or around puberty), high-pitched voice, sparse facial hair, hypogonadism (dysfunctional gonads), oligozoospermia (low sperm count), small testes, micropenis (an ususually small penis), advanced bone maturation, an earlier peak height velocity (an accelerated rate of growth in regards to height), and short final stature due to early epiphyseal closure. The incidence of gynecomastia appears to be 100%, with 20 of 30 male cases opting for mastectomy according to a review.

In females, symptoms of AES include isosexual precocity (precocious puberty with phenotypically-appropriate secondary sexual characteristics), macromastia (excessively large breasts), an enlarged uterus, menstrual irregularities, and, similarly to males, accelerated bone maturation and short final height. Of seven females described in one report, three had macromastia (rate of ~43%). A 10-year-old girl with gigantomastia has subsequently also been described.

Fertility, though usually affected to one degree or another—especially in males—is not always impaired significantly enough to prevent sexual reproduction, as evidenced by vertical transmission of the condition by both sexes.

The exact genetic nature of each particular case of KS / HH will determine which, if any, of the non-reproductive features will occur. The severity of the symptoms will also vary from case to case. Even family members will not show the same range or severity of symptoms.

KS / HH is most often present from birth but adult onset versions are found in both males and females. The hypothalamic-pituitary-gonadal axis (HPG axis) functions normally at birth and well into adult life giving normal puberty and normal reproductive function. The HPG axis then either fails totally or is reduced to a very low level of GnRH release, in adult life with no obvious cause such as a pituitary tumour. This will lead to a fall in testosterone or oestrogen levels and infertility.

Functional hypothalamic amenorrhoea is seen in females where the HPG axis is suppressed in response to physical or psychological stress or malnutrition. It is reversible with the removal of the stressor.

Some cases of KS / HH appear to reverse during adult life where the HPG axis resumes its normal function and GnRH, LH, and FSH levels return to normal levels. This occurs in an estimated 10 to 20% of cases, primarily normosmic CHH cases rather than KS cases and only found in patients who have undergone some form of testosterone replacement therapy.

It is only normally discovered when testicular volume increases while on testosterone treatment alone and testosterone levels return to normal when treatment is stopped. This type of KS / HH rarely occurs in cases where males have had a history of un-descended testes.

Affected individuals with KS and other forms of HH are almost invariably born with normal sexual differentiation; i.e., they are physically male or female. This is due to the human chorionic gonadotrophin (hCG) produced by placenta at approximately 12 to 20 weeks gestation (pregnancy) which is normally unaffected by having KS or CHH.

People with KS / HH lack the surge of GnRH, LH, and FSH that normally occurs between birth and six months of age. This surge is particularly important in infant boys as it helps with testicular descent into the scrotum. The surge of GnRH/LH/FSH in non KS/HH children gives detectable levels of testosterone in boys and oestrogen & progesterone in girls. The lack of this surge can sometimes be used as a diagnostic tool if KS / HH is suspected in a newborn boy, but is not normally distinct enough for diagnosis in girls.

It is normally difficult to distinguish a case of KS / HH from a straightforward constitutional delay of puberty. However, if puberty has not started by either age 14 (girls) or 15 (boys) and one or more of the non-reproductie features mentioned belowe is present then a referral to reproductive endocrinologist might be advisable.

The features of Kallmann syndrome (KS) and other forms of hypogonadotropic hypogonadism (HH) can be split into two different categories; "reproductive" and "non reproductive".

Hypergonadism is a condition where there is a hyperfunction of the gonads. It can manifest as precocious puberty, and is caused by abnormally high levels of testosterone or estrogen, crucial hormones for sexual development. In some cases, it may be caused by a tumor, which can be malignant but mostly benign. Anabolic steroids may also be a major cause of high androgen and/or estrogen functional activity. Symptoms of the condition may include precocious puberty, rapid growth in adolescents, high libido, acne, excessive hairiness, and others.

The symptoms of isolated 17,20-lyase deficiency, in males, include pseudohermaphroditism (i.e., feminized, ambiguous, or mildly underdeveloped (e.g., micropenis, perineal hypospadias, and/or cryptorchidism (undescended testes)) external genitalia), female gender identity, and, in non-complete cases of deficiency where partial virilization occurs, gynecomastia up to Tanner stage V (due to low androgen levels, which results in a lack of suppression of estrogen); in females, amenorrhoea or, in cases of only partial deficiency, merely irregular menses, and enlarged cystic ovaries (due to excessive stimulation by high levels of gonadotropins); and in both sexes, hypergonadotropic hypogonadism (hypogonadism despite high levels of gonadotropins), delayed, impaired, or fully absent adrenarche and puberty with an associated reduction in or complete lack of development of secondary sexual characteristics (sexual infantilism), impaired fertility or complete sterility, tall stature (due to delayed epiphyseal closure), eunuchoid skeletal proportions, delayed or absent bone maturation, and osteoporosis.

The symptoms of Leydig cell hypoplasia include pseudohermaphroditism (i.e., feminized, ambiguous, or relatively mildly underdeveloped (e.g., micropenis, severe hypospadias, and/or cryptorchidism (undescended testes)) external genitalia), a female gender identity or gender variance, hypergonadotropic hypogonadism (hypogonadism despite high levels of gonadotropins), delayed, impaired, or fully absent puberty with an associated reduction in or complete lack of development of secondary sexual characteristics (sexual infantilism), impaired fertility or complete sterility, tall stature (due to delayed epiphyseal closure), eunuchoid skeletal proportions, delayed or absent bone maturation, and osteoporosis.

The root cause of AES is not entirely clear, but it has been elucidated that inheritable, autosomal dominant genetic mutations affecting "CYP19A1", the gene which encodes aromatase, are involved in its etiology. Different mutations are associated with differential severity of symptoms, such as mild to severe gynecomastia.

Excessive menstruation between puberty and 19 years of age is called puberty menorrhagia. Excessive menstruation is defined as bleeding over 80 ml per menstrual period or lasting more than 7 days. The most common cause for puberty menorrhagia is dysfunctional uterine bleeding. The other reasons are idiopathic thrombocytopenic purpura, hypothyroidism, genital tuberculosis, polycystic ovarian disease, leukemia and coagulation disorders. The most common physiological reason for puberty menorrhagia is the immaturity of hypothalamic-pituitary-ovarian axis, leading to inadequate positive feedback and sustained high estrogen levels. Most patients present with anemia due to excessive blood loss.

The patient is assessed with a thorough medical history, physical examination (to look for features of anemia), gynaecological examination (to rule out local causes) and laboratory investigations (to rule out coagulopathies and malignancy). It is mandatory to exclude pregnancy. The treatment is determined based on the cause of menorrhagia. In case of puberty menorrhagia due to immaturity of hypothalamic axis, hormonal therapy is beneficial. Treatment for blood loss should be done simultaneously with iron therapy in mild to moderate blood loss and blood transfusion in severe blood loss.

Isolated 17,20-lyase deficiency (ILD), also called isolated 17,20-desmolase deficiency, is a rare endocrine and autosomal recessive genetic disorder which is characterized by a complete or partial loss of 17,20-lyase activity and, in turn, impaired production of the androgen and estrogen sex steroids. The condition manifests itself as pseudohermaphroditism (partially or fully underdeveloped genitalia) in males, in whom it is considered to be a form of intersex, and, in both sexes, as a reduced or absent puberty/lack of development of secondary sexual characteristics, resulting in a somewhat childlike appearance in adulthood (if left untreated).

Unlike the case of combined 17α-hydroxylase/17,20-lyase deficiency, isolated 17,20-lyase deficiency does not affect glucocorticoid production (or mineralocorticoid levels), and for that reason, does not result in adrenal hyperplasia or hypertension.

Mutations that result in some residual 21-hydroxylase activity cause milder disease, traditionally termed simple virilizing CAH (SVCAH). In these children the mineralocorticoid deficiency is less significant and salt-wasting does not occur. However, genital ambiguities are possible.

The symptoms of CAH vary depending upon the form of CAH and the sex of the patient. Symptoms can include:

Due to inadequate mineralocorticoids:

- vomiting due to salt-wasting leading to dehydration and death

Due to excess androgens:

- functional and average sized penis in cases involving extreme virilization (but no sperm)

- ambiguous genitalia, in some females, such that it can be initially difficult to identify external genitalia as "male" or "female".

- early pubic hair and rapid growth in childhood

- precocious puberty or failure of puberty to occur (sexual infantilism: absent or delayed puberty)

- excessive facial hair, virilization, and/or menstrual irregularity in adolescence

- infertility due to anovulation

- clitoromegaly, enlarged clitoris and shallow vagina

Due to insufficient androgens and estrogens:

- Undervirilization in XY males, which can result in apparently female external genitalia

- In females, hypogonadism can cause sexual infantilism or abnormal pubertal development, infertility, and other reproductive system abnormalities

Virilization of genetically female (XX) infants usually produces obvious genital ambiguity. Inside the pelvis, the ovaries are normal and since they have not been exposed to testicular antimullerian hormone (MIF), the uterus, fallopian tubes, upper vagina, and other mullerian structures are normally formed as well. However, the high levels of testosterone in the blood can enlarge the phallus, partially or completely close the vaginal opening, enclose the urethral groove so that it opens at the base of the phallus, on the shaft or even at the tip like a boy. Testosterone can cause the labial skin to become as thin and rugated as a scrotum, but cannot produce palpable gonads (i.e., testes) in the folds.

Thus, depending on the severity of hyperandrogenism, a female infant can be mildly affected, obviously ambiguous, or so severely virilized as to appear to be a male. Andrea Prader devised the following Prader scale as a way of describing the degree of virilization.

- An infant at stage 1 has a mildly large clitoris and slightly reduced vaginal opening size. This degree may go unnoticed or may be simply assumed to be within normal variation.

- Stages 2 and 3 represent progressively more severe degrees of virilization. The genitalia are obviously abnormal to the eye, with a phallus intermediate in size and a small vaginal opening.

- Stage 4 looks more male than female, with an empty scrotum and a phallus the size of a normal penis, but not quite free enough of the perineum to be pulled onto the abdomen toward the umbilicus (i.e., what is termed a chordee in a male). The single small urethral/vaginal opening at the base or on the shaft of the phallus would be considered a hypospadias in a male. X-rays taken after dye injection into this opening reveal the internal connection with the upper vagina and uterus. This common opening can predispose to urinary obstruction and infection.

- Stage 5 denotes complete male virilization, with a normally formed penis with the urethral opening at or near the tip. The scrotum is normally formed but empty. The internal pelvic organs include normal ovaries and uterus, and the vagina connects internally with the urethra as in Stage 4. These infants are not visibly ambiguous, and are usually assumed to be ordinary boys with undescended testes. In most cases, the diagnosis of CAH is not suspected until signs of salt-wasting develop a week later.

When the genitalia are determined to be ambiguous at birth, CAH is one of the leading diagnostic possibilities. Evaluation reveals the presence of a uterus, extreme elevation of 17OHP, levels of testosterone approaching or exceeding the male range but low AMH levels. The karyotype is that of an ordinary female: 46,XX. With this information, the diagnosis of CAH is readily made and female sex confirmed.

Evaluation of ambiguous genitalia is described in detail elsewhere. In most cases it is possible to confirm and assign female sex within 12–36 hours of birth. The exception are the rare, completely virilized genetic females (Prader stage 5), who present the most challenging assignment and surgery dilemmas, discussed below.

When the degree of ambiguity is obvious, corrective surgery is usually offered and performed. As reconstructive surgery on infant genitalia has become a focus of controversy, the issues are described in more detail below.