Delayed puberty is usually considered if a girl has not menstruated by the age of 16 or if she has no signs of secondary sex characteristics development by the age of 14 and in a boy aged 15.5 years without testicular enlargement. Puberty also said to be delayed if the onset is appropriate but lack of progression of secondary sexual maturation over a two year period or lack of menarche 5 years after breast budding.
The most common cause of primary amenorrhea is delayed puberty due to some genetic factor that delays physical development.Data suggest that environmental exposure to lead may delay growth and pubertal development in girls, although confirmation is warranted in prospective studies.
Discovery made independently by both Harvard and French researchers that a gene called GPR54 is defective in children with a rare disorder that inhibits puberty's onset. To better understand what role GPR54 plays in the initiation of puberty, as well as learn about KiSS-1, which in earlier rodent studies had been identified as a molecule that activates a signal receptor of GPR54, the researchers looked to the nonhuman primate, the only animal with a reproductive system in common with the human's.
The pituitary gonadotropins luteinizing hormone and follicle-stimulating hormone (FSH) regulate the production of sex steroids necessary for pubertal development and fertility. Inherited genetic defects that cause hypogonadism have been identified at multiple levels of the hypothalamic–pituitary–gonadal axis.
Delay of puberty may also occur due to undernutrition, many forms of systemic disease, or to defects of the reproductive system (hypogonadism) or the body's responsiveness to sex hormones.In girls, breasts develop first. Then, hair starts growing in the pubic area. Next, hair starts growing in the armpits. In girls, acne usually starts around 13 years of age. Menstruation (the period) usually happens last.
In boys, the testicles and the penis get bigger first. Then hair grows in the pubic area and the armpits. A small amount of breast tissue might develop at this time. The voice becomes deeper. Muscles grow. Last, acne and facial hair show up.
In general, children and teens who develop hypothyroidism may have delay of puberty.Ninety seven percent of girls have reached Tanner breast or pubic hair stage 2 by age 13.2 years and boys have testicular volume 4ml or more by age 14.2. The causes of delayed puberty are as follows:
a) Boys: Noonan syndrome, Klinefelter syndrome, Testicular damage due to irradiation and chemotherapy and Kallman syndrome.
b) Girls: Turner syndrome, ovarian damage by irradiation and chemotherapy.
c) Both sex: Constitutional delay of growth and puberty; Hypogonadotrophic hypogonadism, Multiple pituitary hormone , Chronic systemic disease & malnutrition, Brain disorders due to tumors and irradiation and Anorexia nervosa, heavy exercise
induced amenorrhea.
Study shown that when carp are subjected to stress, the development of their genital organs is delayed, so that they reach puberty later. It is likely that the stress hormone cortisol plays a major role in delaying puberty.The researchers assumed that the hormone cortisol, which is released when an animal is under stress, plays a major role in this.
Adult men with a history of constitutionally delayed puberty have decreased radial and spinal bone mineral density. These findings suggest that the timing of puberty is an important determinant of peak bone density in men.Men in whom puberty was delayed may be at increased risk for osteoporotic fractures when they are older.
Diagnosis :
The sexual development such as testicular size, phallic length, sexual hair, and breast development should be quantified. Dietary history is helpful. Growth velocity, bone age should be ascertained. Family history is vital. The majority of healthy children who enter puberty late have constitutional delay and a positive family history provides confirmation.
A history of intensive physical training by a girl may have exercise induced delayed puberty with amenorrhea and oestradiol, LH, FSH, prolactin are of prepubertal levels. Persistently small testis (1ml size) isconsistent with gonadotrophin, LH deficiency. Hyposmia points to Kallman syndrome, which is an X-linked dominant disorder. Webbing of the neck suggests
Turner syndrome. Tall stature is found in boys with Klinefelter syndrome.
The endocrine assessment includes basal levels of sex hormones, gonadotropins,adrenal androgens and prolactin. GnRH and hCG stimulation may be done. A karyotype should be performed. Pelvic ultrasound is useful and testicular biopsy in male may be indicated. Nonfunctional testes (vanishing testes syndrome) is indicated by absence of plasma testosterone response to hCG stimulation.
Treatment:
Depends on the cause. Sex hormone replacement may be helpful in many of the causes in the absence of specific treatment.
In constitutional delay, a 3-6 months monthly course of testosterone accelerate the pubertal development.
In hypogonadism,sex steroid with hCG and FSH is helpful.
Researchers have discovered the precise chemical chain reaction that could be the much-sought-after puberty trigger: The KiSS-1 gene, which produces a protein in the hypothalamus, a part of the brain, which regulates metabolic activity. When the protein connects with a receptor on another gene called GPR54, puberty is believed to begin. This knowledge may guide the development of better drugs for treating hormone disorders related to puberty.
Using a mouse model has determined that the absence in the brain's hypothalamus of a gene called TTF-1 causes a delay in the onset of female puberty.This work is of particular interest to those investigating both the delay and early onset of puberty in young women.
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