The goal of this study is to see whether kisspeptin, a naturally occurring hormone, can stimulate the release of other reproductive hormones in men and women with idiopathic hypogonadotropic hypogonadism (IHH). The investigators are also examining whether kisspeptin can help women release eggs from their ovaries. Kisspeptin will be administered SC for two weeks in a pulsatile fashion. Ultrasound monitoring of ovarian follicular growth (for women) and frequent blood sampling (every 10 minutes for up to 70 minutes) will be performed to assess the physiologic response to kisspeptin over time. Funding Source: FDA OOPD

Assignment: All study subjects will undergo the same interventions. Delivery of Interventions: * Each subject will undergo a review of their medical history, physical exam, and screening laboratories. * A single SC injection of leuprolide acetate may be administered approximately six days before kisspeptin administration. (Previously administration of Gonadotropin Releasing Hormone (GnRH) was used in this study.) * A pelvic ultrasound will be performed on women to assess baseline follicular size. * A pump will be placed to administer pulsatile SC kisspeptin for two weeks. * During the course of kisspeptin administration, subjects will * Undergo q10 min blood sampling (approximately 10 sessions, 70 minutes each) * For women, undergo pelvic ultrasounds (approximately 4 sessions) * Optional q10 min sampling up to 8 hours may take place before and after the course of kisspeptin