Clinical Trial: Effect of Cinacalcet on Parathyroid Hormone Secretion in Children and Adolescents With Hypophosphatemic Rickets
Study Status: Completed
Recruit Status: Unknown status
Study Type: Interventional
Official Title: Effect of Calcimimetic (Cinacalcet) on Phosphate-Induced Hyperparathyroidism in Children With Hypophosphatemic Rickets
Brief Summary: This study will measure the effect of cinacalcet (Sensipar) on parathyroid hormone (PTH) secretion in children and adolescents with hypophosphatemic rickets (XLH). The investigators are seeking evidence that patients with XLH may benefit from treatment with cinacalcet by achieving better control of PTH secretion.
Detailed Summary:
X-linked hypophosphatemic rickets (XLH) is an X-linked dominant genetic disorder. Common findings are low serum phosphate and inadequate 1,25(OH)2 vitamin D production. It is generally believed that the primary defect in XLH is impaired renal tubular transport of phosphate coupled with abnormal regulation of the enzyme responsible for the 1-alfa hydroxylation of 25(OH) vitamin D. The current treatment of children with XLH is large oral doses of phosphate and 1,25-dihydroxyvitamin D. There are two common side effects to this treatment; nephrocalcinosis and secondary hyperparathyroidism (HPT). The latter at times may cause hypertension, hypercalcemia, and permanent renal damage. The complication of secondary hyperparathyroidism is seen in 20% of the patients. The release of PTH from the glands into the circulation is tightly regulated by serum calcium concentration. The glands "read" serum calcium concentration via Ca sensing receptors (CaR) which are located at the surface of the glands. Calcimimetics are compounds that allosterically modulate the CaR, thereby enhancing its sensitivity to circulating serum calcium concentrations and consequently decreasing PTH secretion. When used in primary HPT, they rapidly reduce PTH level and normalize serum calcium concentration.
Cinacalcet is a calcimimetic agent recently approved by the FDA for treating hypercalcemia in patients with parathyroid carcinoma and secondary HPT in patients with chronic renal disease. Cinacalcet was found to be effective in decreasing both PTH level and the calcium X phosphorous ion product in dialysis patients.
The goal of our proposed acute study is to see whether concomitant administration of Cinacalcet and phosphate, to patients with XLH, will block completely or partially secretion of PTH (day 2), expected to be seen following administration
Sponsor: Children's Mercy Hospital Kansas City
Current Primary Outcome: The primary outcome will be the effect of cinacalcet on serum PTH. [ Time Frame: PTH will be measured at time 0 and then every 30 minutes for 4 hours after receiving the medications ]
Original Primary Outcome: The primary outcome will be the effect of Cinacalcet on serum PTH. PTH will be measured at time 0 and then every 30 minutes for 4 hours after receiving the medications.
Current Secondary Outcome: Secondary outcome will be the effect of the calcimimetic on mineral homeostasis; ionized calcium, total calcium, and phosphate will be measured. [ Time Frame: At time 0 and then every 30 minutes for 4 hours after receiving the medications ]
Original Secondary Outcome: Secondary outcome will be the effect of the calcimimetic on minerals homeostasis. ionized Calcium, total calcium, and Phosphate will be measured at time 0 and then every 30 minutes for 4 hours after receiving the medications.
Information By: Children's Mercy Hospital Kansas City
Dates:
Date Received: September 13, 2005
Date Started: June 2005
Date Completion:
Last Updated: October 22, 2007
Last Verified: August 2005
