PROTOCOL OUTLINE: Phase I: Patients undergo fasting for urine and blood endocrine assessments. First morning urine is collected for measurement of 6-sulphatoxymelatonin (6-SMT). Following a medical history and a physical examination, patients undergo measurement of serum levels of free thyroxine, thyroid stimulating hormone (TSH), prolactin, insulin-like growth factor I (IGF-I), dehydroepiandrosterone-sulfate (DHEA-S), free and total testosterone (males only), and baseline growth hormone (GH). Female patients also provide a menstrual history and undergo screening for hypogonadism. Patients then undergo GH stimulation testing comprised of measurement of serum GH levels before and on 6 occasions during the 3 hours after receiving glucagon IV.