Delayed puberty overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Puberty is described as delayed when a boy or girl has passed the usual age of onset of puberty with no physical or hormonal signs that it is beginning. Puberty may be delayed for several years and still occur normally, in which case it is considered constitutional delay, a variation of healthy physical development. 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.
Historical Perspective
Studying the archaic humans in Pleistocene (i.e., greater than 10,000 years ago), it assumed that puberty was correlated with productivity in females. The age of menarche was between 7 and 13 years. Researchers have found that in a Turkana boy (from the species of Homo erectus) from 1.6 million years ago, the puberty was earlier than today humans; however, their final height were more than modern humans. The discovery and growth of agriculture in archaic world is the main reason of delaying puberty age, through a negative impact on child growth. Agricultural communities in contrast with hunter-gatherer communities, experienced tougher life style and rose with so many nutrition deficits; that may lead to their delayed puberty. Regarding that life style was growing and the complexity of societies were increasing in the past, the process of becoming adult from child was elongated and delayed puberty happened.
Classification
Delayed puberty is almost always due to physiologic exaggerated prolongation of puberty timing in boys, a condition called "constitutional delay of growth and puberty (CDGP)". But the disease may sometimes has another pathophysiologies, such as hypergonadotropic hypogonadism, permanent hypogonadotropic hypogonadism, and functional hypogonadotropic hypogonadism.
Pathophysiology
It is absolute that delayed puberty is the result of any disturbances in hypothalamus-pituitary-gonadal (HPG) axis. Delayed puberty has found to be on a genetic basis, most of the times. It is assumed that the main factor in determining the puberty timing is genetic elements. In case of constitutional delay of growth and puberty (CDGP), researchers suggested 50-75% of positive family history of delayed puberty. About 25 various genes, in 3 different group of Kallman syndrome related genes, hypothalamus-pituitary-gonadal (HPG) axis related genes, and obesity related genes, play roles in delayed puberty. Macroscopic pathology of delayed puberty is based on Tanner staging in specific ages. Microscopic evaluation of ovaries in a patient with delayed puberty may reveal the presence of normal cubical epithelium. The ovary has some dense fibrous tissue, about 0.4 mm thick band, in the cortex. The band is extended under the tunica albuginea, devoid of follicles. Under the fibrous band there will be numerous small follicles. These follicles consist of primordial (51%), intermediary (42%), and primary (7%) follicles.
Causes
Delayed puberty may be caused by endocrine or genetic causes. The most common endocrine causes of delayed puberty is hypothalamus-pituitary-gonadal (HPG) axis disorders. The most common genetic causes of delayed puberty is Kallmann syndrome. There are various genes that may be related to delayed puberty, among which the kisspeptin system genes (KISS1 and KISS1R) are the most important genes.
Differentiating Delayed puberty from Other Diseases
Delayed puberty must be differentiated from other diseases that cause latency in secondary sexual characteristics development, such as constitutional delay of puberty, hypopituitarism, and chromosomal abnormalities. Chromosomal abnormalities are Turner's syndrome, Klinefelter's syndrome, and Noonan's syndrome.
Epidemiology and Demographics
The incidence of delayed puberty (hypogonadotropic hypogonadism) is approximately 1-10 cases per 100,000 individuals worldwide.The precise prevalence of delayed puberty is not known completely. The whole puberty disorders prevalence is about 3000 cases per 100,000 individuals worldwide. Regarding the definition of delayed puberty, the disease commonly affects children under 15 years of age. Delayed puberty usually affects individuals of all races, equally. Definite diagnosis upon the mean age of puberty onset in any specific societies can help to reduce the effects of ethnicity on delayed puberty epidemiology. Boys are more commonly affected by delayed puberty (constitutional delay of puberty) than girls.
Risk Factors
The most potent risk factor in the development of delayed puberty is hypothalamus-pituitary-gonadal (HPG) axis disturbance. Other risk factors are including genetic, endocrinologic, and environmental; which may disturb the HPG axis.
Screening
According to the US Preventive Services Task Force (USPSTF), screening for delayed puberty is not recommended.