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THE TIMING OF PUBERTY
Puberty is the process of the body maturing into adulthood, with the appearance of secondary sexual characteristics and the development of the ovaries or testes, eventually resulting in the ability to have children. The physical characteristics of puberty include breast development in girls, enlargement of the penis and the growth of testes in boys, as well as pubic hair and underarm hair in both sexes. Development of the testes in boys can be easily assessed through simple examination in the clinic to establish the stage of puberty they have reached by the size of the testes. The doctor will assess the size of the testes by comparing them to a set of standard beads called an orchidometer. The equivalent assessment of the ovaries in girls connot be done in the clinic and may require the simple technique of using an ultrasound scan to assess the maturity of the ovaries.
The average age for the onset of puberty in boys is 12 years and in girls 11½ years. Surprisingly, the age difference between boys and girls starting puberty is only half a year, although it is often though to be much more. In girls, the start of breast development, which is an early event in their puberty, happens at the same time as the growth spurt. In boys, the pubertal changes involving the growth of the testes and penis are less socially obvious and the growth spurt, being a relatively late event, happens mid-way during the physical changes. The comparatively late start of the growth spurt in boys explains why the difficulties associated with pubertal delay are more common in boys than girls. It may entirely normal for a boy to enter puberty at 14 years of age and not experience a growth spurt until 17 years, by which time he would be considerably shorter than his peers, and may be experiencing social problems.
The onset of puberty in boys and girls triggered by the increase in gonadotrophin releasing hormone [GnRH] secretion from the hypothalamus which stimulates the pituitary gland. The pituitary gland then release the two gonadotrophins – Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH) – which stimulate the testes or ovaries to develop. This process starts much earlier in childhood than is normally appreciated. There are various glands and hormones that are involved in this process of puberty, which continues as sexual maturation in adult life.
 THE HARMONY OF PUBERTY
The events of puberty have a characteristic pattern in the timing of their appearance. This pattern should remain the same even if the start of puberty is either delayed or early. By this we mean that the development of breasts or genitalia and the appearance of public hair always occur in a fixed order. In addition, the spontaneous growth spurt occurs at a particular stage of either breast development in girls or size of genitalia in boys. Even though the age at which puberty starts may vary considerably between individuals, the same pattern of normal puberty is retained. Indeed, the absence of this normal pattern point to a hormonal abnormality. This pattern will allow your specialist to determine whether your child’s late puberty is a characteristically normal process of delay or whether there is a hormone abnormality which needs investigation. Keeping this normal pattern of the appearance of secondary sexual characteristics, and the timing of the growth spurt, is the most significant feature of constitutional delay and is the key to the diagnosis.
GROWTH AT PUBERTY
It is impossible to assess any young person’s growth during adolescence without relating it to the stage of pubertal development. The two events fit together in a characteristic Way. There is a wide variation in the ages at which puberty begins [between the ages of 9 and 14 years] and the time it takes to progress through puberty. Such variation is illustrated by the “Shaded areas” on the Tanner growth charts during the early teenage years. Growth in this age group depends on what stage the physical signs of puberty are at not on how old the adolescent is.
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