Following intravenous injection, GnRH triggers a prompt, dose-related increase of LH and FSH in humans (Fig. 1.15) and in all vertebrate species in which it has been tested. After a single bolus injection, FSH release is usually delayed compared with LH secretion the values peaking ten to thirty minutes after injection. The response of LH and FSH to GnRH is markedly influenced by the prior GnRH secretory state, by the gonadal steroid milieu, by the state of gonadal activity, by the time course of GnRH injection (i.e. single dose, multiple pulse, or constant infusion), and by the patient's genetic, sex.
