Puberty and adolescence are recognised as periods involving marked endocrine changes that regulate growth and sexual development. Normal pubertal development is known to be centrally driven and dependent upon appropriate gonadotrophin and growth hormone secretion and normal functioning of the hypothalamic-pituitary-gonadal axis. The mechanisms that control the precise timing of the onset of puberty, however, are still not clearly understood but are influenced by many factors, including general health, nutrition, exercise, genetic influences and socio-economic conditions.

Pubertal development

Puberty represents a period of significant growth, hormonal changes and attainment of reproductive capacity. Its onset is marked by a significant increase in the amplitude of pulsatile release of gonadotrophin-releasing hormone (GnRH) by the hypothalamus. This usually occurs between the ages of eight years and 13.5 years in girls and stimulates an increase in pituitary release of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which initially occurs as high-amplitude nocturnal pulses, although eventually both daytime and nocturnal pulsatile release is established. FSH and LH in turn act upon the ovary to promote follicular development and sex steroid synthesis. In the female, this period is characterised clinically by accelerated linear growth, the development of breasts and pubic hair and the eventual onset of menstruation (menarche), which occurs between the ages of 11 and 16 years in most women in the UK (Figure 3.1). Menarche is often used as a marker of pubertal development, as it is an easily identifiable event that can usually be dated with some accuracy (Figure 3.2).