The precise mechanism for timing the onset of puberty have not been defined. There appears to be a decrease in the sensitivity of the feedback mechanisms which regulate the activity of the hypothalamic-pituitary-gonadal axis.
The first event in puberty is a rise in the adrenal androgen dehyroepiandrosterone (DHA). This stage is termed adrenache. Subsequently, increasing levels of LH and FSH result in raised testosterone levels in the male - pubarche - and raised levels of sex steroids in the female - thelarche - which begin their cyclical variation late in puberty. The time of onset is regulated by:
- the physical conditions - for example the fat/lean ratio
- the psychological environment
- an intrinsic clock
Last reviewed 01/2018