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.

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.

• Variation of normal (constitutional delay)
• Prolonged high level of physical exertion / being an athlete
• Systemic disease, e.g. Inflammatory bowel disease, chronic renal failure
• Undernutrition e.g. anorexia nervosa, zinc deficiency
• Hypothalamic defects and diseases e.g. Prader-Willi syndrome
• Pituitary defects and diseases e.g. hypopituitarism, Kallmann syndrome
• Gonadal defects and diseases e.g. Turner syndrome, Klinefelter syndrome
• Absence or unresponsiveness of target organs e.g. androgen insensitivity syndrome, mullerian agenesis
• Other hormone deficiencies and imbalances e.g. hypothyroidism, Cushing’s syndrome

Constitutional delay of puberty must be differentiated from other diseases that cause latency in secondary sexual characteristics development, such as delayed puberty, hypopituitarism, and chromosomal abnormalities. Chromosomal abnormalities are Turner’s syndrome, Klinefelter’s syndrome, and Noonan’s syndrome.

• Constitutional delay of puberty must be differentiated from other diseases that cause latency in secondary sexual characteristics development, such as delayed puberty, hypopituitarism, and chromosomal abnormalities. Chromosomal abnormalities are Turner’s syndrome, Klinefelter’s syndrome, and Noonan’s syndrome.^[1]

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