Puberty

There is no doubt that while many menstrual cycles are initially anovulatory2 some may be ovulatory, often with a long follicular phase. Early menarche is associated with early onset of ovulatory cycles. When menarche occurs below 12 years, 50 per cent of cycles are ovulatory in the first year and virtually all by the fifth year. By contrast, it takes 8–12 years for all cycles to be ovulatory in girls with later onset of menarche. This has important clinical implications for advising adolescents and their parents or carers on the ‘normality’ of their menstrual pattern relative to their age at menarche.

Precocious puberty

Precocious onset of puberty is defined as occurring younger than two standard deviations (SDs) before the average age; that is, earlier than eight years old in females and earlier than nine years in males. Thus, in many individuals, early onset of puberty merely represents one end of the normal distribution. However, a number of pathological conditions may prematurely activate the GnRH-LH/FSH (hypothalamo-pituitary secretory unit) axis, resulting in the precocious onset of puberty. Investigation and treatment of precocious puberty should always be by a paediatric endocrinologist.

Delayed puberty

Delayed puberty is defined as absence of onset of puberty by more than two SDs later than the average age; that is, later than 14 years in females and later than 16 years in males. Delayed puberty may be idiopathic/familial or due to a number of general conditions resulting in undernutrition. Absence of puberty may also be due to gonadal failure (elevated gonadotrophin levels), or impairment of gonadotrophin secretion.

Management depends on cause. Following exclusion of other diagnoses, many patients with constitutional delay are happy to await spontaneous pubertal development. However, severe delay in pubertal onset may be a risk factor for decreased bone mineral density and osteoporosis. In children with hypergonadotrophic hypogonadism, puberty may be induced from any age. However, for others, such as girls with Turner Syndrome, delay in induction to around 14 years old possibly permits maximal response to growth hormone therapy nolvadex Canada.

Menstrual cycle abnormalities

Amenorrhoea

Amenorrhoea (the absence of menstruation) may be temporary or permanent (usually of at least six months’ duration). It is best classified according to its aetiology, or site of origin, and can be subdivided into: disorders of the hypothalamic-pituitary-ovarian-uterine axis generalized systemic disease.

The failure to menstruate by the age of 16 in the presence of normal secondary sexual development, or 14 in the absence of secondary sexual characteristics, warrants investigation. This distinction helps to differentiate reproductive tract anomalies from gonadal quiescence and gonadal failure. Primary amenorrhoea may be a result of congenital abnormalities in the development of ovaries, genital tract or external genitalia or a disturbance of the normal endocrinological events of puberty.