The goal of this study is to test whether the hormone kisspeptin has the potential to prospectively diagnose adolescents with self-resolving or permanent delayed puberty. Some children with delayed puberty will eventually enter puberty on their own. However, some children with delayed puberty have a permanent condition and require medical treatment to undergo puberty. Right now, there is no reliable diagnostic tool to tell whether a child's delayed puberty will be self-resolving or permanent. The hormone kisspeptin has the potential to prospectively diagnose adolescents with self-resolving or permanent delayed puberty.

The investigators are seeking boys (ages 13.5-17 years) and girls (ages 12-17) years with a diagnosis of delayed puberty. Study participation involves 2 outpatient visits and two hospital admissions (one 11-hour, overnight admission and one 6-hour day admission) when subjects will receive two investigational drugs, the naturally occurring hormones kisspeptin and gonadotropin-releasing hormone (GnRH). Subjects will then be followed every 6 months until they reach 18 years of age to determine if their pubertal delay was self-resolved or permanent.