7 Day Continuous Parathyroid Hormone IV Infusion

Study consists of an eight day inpatient visit on the General Clinical Research Center. The investigators' specific aims are to: 1. To define the maximum safe dose of a seven day continuous administration of parathyroid hormone \[PTH(1-34)\] in healthy human volunteers. 2. To estimate the effect of a seven day continuous administration of parathyroid Hormone (PTH) in escalating doses on vitamin D metabolism, markers of bone turnover and fractional excretion of urine.