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Physiologic Regulation of FGF-23

NCT00356512 · Status: COMPLETED · Type: OBSERVATIONAL · Enrollment: 20

Last updated 2017-07-02

No results posted yet for this study

Summary

This study will explore the regulation of fibroblast growth factor-23 (FGF-23). It is a hormone recently identified as a regulator of the blood levels of phosphorus and vitamin D, both of which are essential for overall health and especially important for bone health. The parathyroid hormone (PTH) regulates phosphorus and calcium, but people with hypoparathyroidism or pseudohypoparathyroidism do not have sufficient PTH action. There are genetic diseases that influence FGF-23, causing abnormal metabolism of phosphorus and vitamin D, thus affecting the bones. Also, there are rare tumors that may cause overproduction of FGF-23 causing debilitating bone disease.

Patients ages 18 and older who have low PTH levels, or are resistant to PTH action, and take calcitriol and calcium supplements, who are not pregnant, and who do not have kidney disorders may be eligible for this study. During the 4-day study, patients will be provided with a controlled diet that has a lower than usual phosphorus content. On day 1, patients will be admitted to the NIH Clinic Center and undergo blood and urine tests to measure calcium, phosphorus, vitamin D, and FGF-23. They will continue with their regular medicine for hypoparathyroidism. On that day and throughout the study, patients will fast from 10:00 p.m. to 8:00 a.m. the following day. On day 2, patients will continue fasting until 4:00 p.m. A tube will be placed in the vein of each arm: one for drawing blood and the other for infusing calcium. Just one intravenous (IV) line will be used on the other days. Patients will receive calcium chloride for 8 hours, at a dose carefully monitored by a machine. The purpose is to bring the blood calcium level to the high normal range or just above. Blood and urine samples will be collected periodically, to check for effects of calcium chloride on FGF-23 and PTH. On days 3 and 4, patients will not take calcitriol and calcium but will receive injections of PTH, under the skin, two times each day. On day 3, blood and urine samples will be again be collected for analysis. On day 4, patients will receive one dose of calcitriol by IV. The total amount of blood drawn during this study will be about 5 ounces.

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Conditions

  • Hypoparathyroidism

Sponsors & Collaborators

  • National Institute of Dental and Craniofacial Research (NIDCR)

    lead NIH

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2006-07-19
Primary Completion
2009-09-02

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00356512 on ClinicalTrials.gov