People whose test results are abnormal will be seen at the NIH outpatient clinic for a medical history, physical examination, and blood tests; bedtime saliva collection; two 24-hour urine collections; and a 2-day 2-mg DST, followed by administration of corticotropin-releasing hormone (CRH). CRH is a naturally occurring hormone that causes cortisol levels to rise. Pre-treatment with dexamethasone prevents CRH from causing an increase in cortisol in healthy people, but not in patients with Cushing s syndrome. For the 2-day DST, the subject takes 0.5 mg dexamethasone every 6 hours for eight doses. Two hours after the last dose, CRH is injected through a catheter (thin plastic tube) inserted into an arm vein. Blood is drawn just before giving CRH to measure dexamethasone and cortisol levels and after giving CRH to measure cortisol levels.