HEXT (Hypo EXTended): Effect of PTH on Skeleton in Hypoparathyroidism

This is an open-label study of PTH(1-84) treatment that seeks: 1. To determine the actions of PTH(1-84) to provide long term control of serum calcium and urinary calcium excretion with use of standard amounts of calcium and vitamin D supplementation. 2. To determine the extent to which PTH(1-84) improves quality-of-life on long-term basis. 3. To establish the safety of PTH(1-84) when administered for up to 12 years. 4. To attempt to quantify improvements in the typical signs/symptoms of hypoparathyroidism post PTH administration. There will be one visit conducted every six months in the study offices of the principal investigator, Dr. John Bilezikian. In addition to these visits, there will be, for new patients who have not used PTH (1-84) before, a Screening Visit four weeks prior to the baseline visit for the purpose of performing screening labs as well as a Pre-Baseline Local Quest Lab performed to ensure stability prior to Baseline.