LH is released from the pituitary gland along with FSH in response to GnRH release into the hypophyseal portal system.  Pulsatile GnRH release causes pulsatile LH and FSH release to occur, which modulates and maintains appropriate levels of bioavailable gonadal hormone: testosterone in males and estradiol in females subject to the requirements of a superior feedback loop.  In females the levels of LH is typically 1–20 IU/L during the reproductive period and is estimated to be 1.8–8.6 IU/L in males over 18 years of age.