Establishment of tonic ovarian estrogen secretion for extended therapeutic regimens

A regimen for the therapeutic management of a gonadal-steroid dependent condition in a mammal constitutes reducing the estrogen supply thereof by means of administration of a GnRH antagonist in an amount effective to inhibit proliferation of endometrial tissue without substantially stopping the production of endogenous estrogen. A method of determining whether the reduced estrogen supply in an individual is such that the concentration of estradiol has been suppressed to an optimized level appropriate to the therapeutic management of the gonadal-steroid dependent condition such as endometriosis in that individual by the administration of a GnRH antagonist at a given dosage level involves titering the dosage, e.g., by conducting a progesterone challenge test and optimal regimen doses of a GnRH antagonist.