The earliest hormonal changes of puberty, found even before the onset of physical changes, is night-time episodic secretion of gonadotrophins (Fig. 13.14). This occurs at a time when levels of the readily releasable gonadotrophins in the pituitary gland are increased, as detected by the administration of GnRH. This is followed by increased episodic secretion of gonadotrophins during the day, until there no longer remains a diurnal variation in gonadotrophin secretion.
