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

Hypoparathyroidism

Hypoparathyroidism, Hypopara, HPTH, Hypocalcemia, Hypercalciuria, PTH, PTH(1-84)

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.

Hypoparathyroidism is a rare disorder in which parathyroid hormone (PTH) is markedly decreased or absent from the circulation. It is the only remaining hormone deficiency state for which replacement with the missing hormone has been heretofore unavailable. The hypoparathyroid state is due either to autoimmune destruction of the parathyroid glands or to loss of parathyroid function after neck surgery. Without PTH, calcium homeostasis is markedly abnormal, the most salient clinical feature of which is a reduced serum calcium concentration. The hypocalcemia is associated with other important abnormalities such as markedly reduced parameters of bone turnover. PTH(1-84) is the ideal therapeutic approach to hypoparathyroidism. The current mainstay of therapy, calcium and vitamin D, has important clinical limitations. Large doses of calcium and vitamin D are required and often associated with hypercalciuria and vitamin D toxicity. Moreover, this approach does not correct the skeletal deficiencies resident in the bones themselves due to lack of PTH. In contrast, PTH(1-84) replaces precisely what is missing in this disorder. The research question is: What are the long-term safety and efficacy parameters of PTH(1-84) therapy in hypoparathyroidism? Preliminary data suggest that treatment with PTH(1-84) for up to 4 years improves control of the serum and urine calcium concentration safely. Since hypoparathyroidism is a chronic disorder, it is important to know whether these salutary effects continue to be seen beyond 4 years. There is a need to determine the safety and efficacy treatment of PTH(1-84) in hypoparathyroidism beyond 4 years.

United States

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