Vitamin D and its analogs, the conventional treatment for hypoparathyroidism, are associated with chronic hypercalciuria due to their lack of calcium-retaining effect in the kidney. This side effect usually occurs even while maintaining the serum calcium in the normal range and may lead to calcium deposition in the kidney (nephrocalcinosis) and renal insufficiency. This study examines the long-term effects of subcutaneous parathyroid hormone (PTH) therapy on calcium metabolism, bone, and renal function. Our previous short-term pilot study comparing subcutaneous PTH with calcitriol demonstrated a significant decrease in urinary calcium excretion during PTH therapy. Based upon these results, we hypothesized that treatment with PTH is more physiologic and provides improved long-term metabolic control. Additionally, treatment with PTH may avoid the adverse side effects on the kidney that are associated with conventional therapy. Patients initially come to the Clinical Center for a two week inpatient evaluation. Subsequent follow-up will occur semiannually on an outpatient basis.