Effectiveness of Paricalcitol in Reducing Parathyroid Hormone (PTH) Levels in X-linked Hypophosphatemic Rickets

Hyperparathyroidism Clinical Trial

Official title: The Role of Parathyroid Hormone in the Pathogenesis of Skeletal Disease in X-linked Hypophosphatemic Rickets (XLH)

Status Completed

Clinical Trial Summary

The purpose of this study is to determine the effectiveness of paricalcitol, a form of synthetic vitamin D, in lowering parathyroid hormone (PTH) levels and reducing disease symptoms in children and adults with X-linked hypophosphatemic (XLH) rickets.

Clinical Trial Description

XLH rickets is a rare inherited disorder in which the bones become painfully soft and bend easily because of a phosphate deficiency. This genetic defect causes the kidneys to allow excretion of an inappropriately high amount of phosphate into the urine. The kidneys are also unable to convert vitamin D into a form usable by the body, resulting in inadequate amounts of active vitamin D. Because vitamin D is needed to absorb calcium and phosphate from the intestine, this deficiency further reduces phosphate levels. Without the sufficient phosphate needed for normal bone growth, individuals with XLH rickets typically develop skeletal malformations, bone pain, and abnormally bowed legs. Hyperparathyroidism, a condition in which the parathyroid glands excrete excess amounts of PTH, also occurs frequently in individuals with XLH rickets, and may play a significant role in the skeletal complications associated with XLH rickets. The purpose of this study is to determine the effectiveness of paricalcitol in lowering PTH levels and reducing disease symptoms in individuals with XLH rickets.

This study will last 12 months. Participants will be randomly assigned to receive either paricalcitol or placebo, taken in the form of two pills daily for the duration of the study. During a baseline 3-day inpatient hospital stay, participants will undergo a physical exam, a cardiac ultrasound, a bone scan, blood collection, and a radiographic skeletal survey. The skeletal survey will include x-rays of various body parts. Participants who are 18 years or younger will not undergo the radiographic skeletal survey. Study visits for all participants will occur every 2 months until the end of the study. These visits will include a physical exam, review of disease symptoms, blood and urine collection, and a check of medication compliance. ;

Related Conditions & MeSH terms

• Familial Hypophosphatemic Rickets
• Hyperparathyroidism
• Hypophosphatemia
• Hypophosphatemia, Familial
• Rickets

• NCT number: NCT00417612
• Study type: Interventional
• Source: Yale University
• Status: Completed
• Phase: Phase 3
• Start date: January 2007
• Completion date: August 2012