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.

After eating, patients undergo adrenocorticotropic hormone stimulation testing comprised of measurement of serum cortisol levels before and at 45 minutes after receiving corticotropin IV. Phase II: Beginning at noon on a different day, patients with any abnormal endocrine tests during phase I undergo 24 hour inpatient dynamic testing of the neuroendocrine system. Patients undergo GH stimulation testing comprised of measurement of serum GH levels before and on 4 occasions during the 2 hours after receiving levodopa. Patients also undergo concurrent thyrotropin releasing hormone (TRH) and gonadotropin releasing hormone (GnRH) stimulation testing comprised of measurement of serum TSH and luteinizing hormone (LH) levels before and at 15, 30, 60, and 90 minutes after receiving TRH and GnRH IV. Patients then undergo overnight metyrapone testing comprised of baseline measurement of serum 11-deoxycortisol and cortisol levels, followed by oral metyrapone with a snack, overnight fasting, and then remeasurement of serum 11-deoxycortisol and cortisol levels.