Delayed puberty pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Pathophysiology
Pathogenesis
- It is absolute that delayed puberty is the result of any disturbances in hypothalamus-pituitary-gonadal (HPG) axis.
- The components of HPG axis is already well identified and oriented, but the main signal of starting the puberty is not cleared completely, yet. It is not obvious that why some children start puberty at 11 and some others start at 14.
- Intact HPG axis is the main factor that a child need to become maturated. The beginning of the pathway is with gonadotropin releasing hormone (GnRH) production from hypothalamus. Then, GnRH stimulates the gonadotropic cells in anterior pituitary gland, producing luteinizing hormone (LH) and follicle stimulating hormone (FSH). Finally, LH and FSH stimulate the gonads maturation to produce the sex-steroids, firing the puberty process.
- Every single failure in the mentioned pathway could lead to postpone the puberty, delayed puberty. The failure may be congenital or acquired during the life.[1]
| Group | Form of disease | Disease | Pathogenesis |
|---|---|---|---|
| Primary hypogonadism | Congenital | Chromosomal abnormality | Lack or disorder of an specific cell line or enzyme that are responsible to produce one of sex-steroids in gonads |
| Gonadal agenesis | Lack of gonads, as main source of sex-steroids | ||
| Acquired | Any external stress to the gonadal tissues | Destruction of gonadal cell line, responsible for producing and secreting sex-steroids | |
| Secondary hypogonadism | Congenital | GnRH deficiency | Lack or disorder of an specific cell line or enzyme that are responsible to produce GnRH in hypothalamus |
| LH and FSH deficiency | Lack or disorder of an specific cell line or enzyme that are responsible to produce LH or FSH in pituitary gonadotropic cells | ||
| Acquired | Any external stress to the hypothalamus or anterior pituitary | Destruction of hypothalamus or anterior pituitary cell line, responsible for producing and secreting GnRH, LH, or FSH |
Genetics
- Delayed puberty is transmitted in [mode of genetic transmission] pattern.
- Genes involved in the pathogenesis of [disease name] include [gene1], [gene2], and [gene3].
- The development of [disease name] is the result of multiple genetic mutations.
Associated Conditions
Gross Pathology
- On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Microscopic Pathology
- On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Normal timing
Approximate mean ages for 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 9 and 14 years of age. They include the occurrence of secondary sex 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 17 or testicular development by the age of 20.
For North American, Indo-Iranian (India, Iran) and European girls
- Thelarche 10y5m (8y–13y)
- Pubarche 11y (8.5–13.5y)
- Growth spurt 10–12.5y
- Menarche 12.5y (10.5–14.5)
- Adult height reached 14.5y
For North American, Indo-Iranian (India, Iran) and European boys
- Testicular enlargement 11.5y (9.5–13.5y)
- Pubic hair 12y (10–14y)
- Growth spurt 12.5–15y
- Completion of growth 17.5
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.
Evaluation
Obviously anyone who is later than average is late in the ordinary sense. There are three indications that pubertal delay may be due to an abnormal cause. The first is simply degree of lateness: although no recommended age of evaluation cleanly separates pathologic from physiologic delay, a delay of 2-3 years or more warrants evaluation.
- In girls, no breast development by 13 years, or no menarche by 3 years after breast development (or by 16).
- In boys, no testicular enlargement by 14 years.
The second indicator is discordance of development. In most children, puberty proceeds as a predictable series of changes in specific order. In children with ordinary constitutional delay, all aspects of physical maturation typically remain concordant but a few years later than average. If some aspects of physical development are delayed, and others are not, there is likely something wrong. For instance, in most girls, the beginning stages of breast development precede pubic hair. If a 12 year old girl were to reach Tanner stage 3 pubic hair for a year or more without breast development, it would be unusual enough to suggest an abnormality such as defective ovaries. Similarly, if a 13 year old boy had reached stage 3 or 4 pubic hair with testes that still remained prepubertal in size, it would be unusual and suggestive of a testicular abnormality.
The third indicator is the presence of clues to specific disorders of the reproductive system. For example, malnutrition or anorexia nervosa severe enough to delay puberty will give other clues as well. Poor growth would suggest the possibility of hypopituitarism or Turner syndrome. Reduced sense of smell (hyposmia) suggests Kallmann syndrome.
Constitutional delay
Children who are healthy but have a slower rate of physical development than average have constitutional delay in growth and adolescence. 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 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.
References
- ↑ Palmert, Mark R.; Dunkel, Leo (2012). "Delayed Puberty". New England Journal of Medicine. 366 (5): 443–453. doi:10.1056/NEJMcp1109290. ISSN 0028-4793.