[Testing of the steroid-related suppressive effect on the hypothalamo-hypophyseal system using twofold stimulation]

Intravenous administration of gonadotropin-releasing hormone (GnRH) induces not only a rapid release of pituitary LH and FSH stored, but also stimulates biosynthesis of these hormones by a long acting process. Repeated injection of GnRH after an interval of 90 to 120 minutes evokes an increased response compared with the first period of stimulation. This pattern of reaction is principally maintained on therapy with steroidal contraceptives. The twofold stimulation provides additional information on hypothalamic-pituitary reactivity exceeding the results yielded by the simple GnRH stimulation test. On the contrary examination of prolactin response to twofold TRH-administration gives no increased diagnostic aid.