• Vitamin D vs PTH effects on bone. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  

• Vitamin D vs PTH effects on calcium metabolism. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  

Drug: Synthetic Human PTH 1-34
N/A

Prior studies (92-CH-0011) have been important in establishing synthetic human parathyroid hormone 1-34 (PTH) as a beneficial treatment for hypoparathyroidism, superior to conventional therapy with calcium and calcitirol. This study will examine the effects of hypoparathyroidism and two different parathyroid hormone (PTH) replacement regimens on the skeleton of children and adults with hypoparathyroidism. Our prior noninvasive studies of bone mass and turnover suggested that although there was no significant effect of long-term treatment with PTH on bone mass, PTH therapy leads to a chronic high bone turnover state. Ultrastructural, cellular, and molecular analyses are now needed to further examine and characterize both the effect of hypoparathyroidism and treatment with replacement PTH on bone. The primary goals of this study are to (1) understand the effect of absent or low levels of PTH (hypoparathyroidism) and its therapeutic replacement by way of PTH (for the maintenance of calcium homeostasis) on the hypoparathyroid skeleton and (2) characterize bone growth both in the absence of PTH in children with hypoparathyroidism and to then compare the same children on replacement doses of PTH. In the first year of the study, patients will receive conventional (calcitriol plus calcium) therapy, during the second year subjects will be treated with PTH (twice daily vs three times daily), and at the end of the second year subjects will be allowed to continue on PTH for up to an additional three additional years. This study presents a unique opportunity, through the study of subjects with hypoparathyroidism and their treatment with PTH, to assess the role of PTH in human skeletal biology.

• INCLUSION CRITERIA:

This study will include patients of both genders (ages 9-55) with biochemically confirmed chronic hypoparathyroidism of at least one year duration. Eighty subjects (30 children and 50 adults) will be enrolled.

EXCLUSION CRITERIA:

Subjects who meet any of the following criteria are not eligible for the study:

• Presence of significant hepatic or kidney disease (GFR less than 25 mL/min).
• Allergy to tetracycline antibiotics.
• Pregnancy.
• Chronic disease that might effect growth or mineral metabolism such as GI disorders.
• Cushing's syndrome or disease and adrenal insufficiency.
• Use of systemic or inhaled corticosteroids within the last 6 months.
• Patients who are calcium infusion dependent and/or do not respond to calcitriol therapy to maintain normal levels of serum calcium will be excluded.
• Seizure disorder requiring antiepileptic medications.
• Treatment with PTH within the two years prior to study entry.