The staging described by Tanner is now the universally accepted method of describing this transitional phase of life. Although pubertal development is continuous, an attempt to understand the process in defined stages can be very helpful. The details are well known and found in all reference texts. However, the description of five distinct stages can lead to misinterpretation unless what happens at each stage is fully understood. As stage 1 is that of the prepubertal child, and stage 5 that of the fully mature individual, there are in reality only three transitional phases of puberty: stage 2— early, stage 3— middle, and stage 4— late. The timing of the key events is what differs between the sexes. In early puberty, defined as testicular enlargement in boys and areolar growth in girls, ex ternal signs are negligible in boys but in girls, growth accelerates fast. By mid- puberty girls have reached peak height velocity and boys’ growth is beginning to speed up. At stage 4 or late puberty most of the external changes in boys such as lowering of the voice, the development of pubic, axillary and facial hair, and rapid growth become apparent and testis volume increases to around 12– 15 ml, whereas in girls the key event is menarche. Table 1 details the mean age and range of the key features of the pubertal growth spurt.
Table1. Key milestones of the adolescent growth spurt in boys and girls indicating how rapidly puberty progresses around the peak stage of development, at what age in the process this occurs and what is the range of each parameter (given in SD). Height increase is given in cm/ yr, puberty parameters in Tanner stages/ yr and testis volume in ml/ yr.
Tanner staging requires conducting a clinical examination and training of the clinician to ensure accuracy. In day- to- day clinical practice, this is not always feasible, possible, or desirable, yet the complete evaluation of growth in a girl over 8 years and a boy over 9 years necessitates knowing what is happening to pubertal development. Thus the use of the puberty ‘phases’ system may be more appropriate. The division of puberty into three phases, prepuberty, in puberty, and completing puberty allows ascertainment by history alone if examination is not possible (Table2), and comparison with the vertical puberty lines on the 2– 18 year or 2– 20 year Childhood and Puberty Close Monitoring RCPCH growth charts can be made. These lines depict the 99.6th and 0.4th centiles for the onset and completion of puberty and contain vertical reminders of the status of each puberty line (Figures1 and 2).
Table2. The phases of puberty as assessed by history
Fig1. Childhood and puberty close monitoring 2– 20 years growth chart for girls. Reproduced with kind permission from RCPCH and Harlow Printing Limited. Copyright 2019 © Royal College of Paediatrics and Child Health.
Fig2. Childhood and puberty close monitoring 2– 20 years growth chart for boys. Reproduced with kind permission from RCPCH and Harlow Printing Limited. Copyright 2019 © Royal College of Paediatrics and Child Health.
The sequence of pubertal events does not normally vary between individuals. It is the timing of the onset of pubertal changes and the rate of progress which does. The childhood component of growth will continue until superseded by the pubertal phase, and variations in growth can usually be explained by what progress has or has not occurred in puberty. Although markedly variable from person to person, total pubertal growth in girls is usually 15– 25 cm and in boys 20– 30 cm, with smaller gains in later maturing adolescents. Hence the importance of pubertal assessment in the evaluation of growth during adolescence.
