MedTrace Logo

Measurement of the Free Fraction of 25-hydroxyvitamin D in Serum

NCT01771380 · Status: COMPLETED · Type: OBSERVATIONAL · Enrollment: 78

Last updated 2015-09-22

No results posted yet for this study

Summary

In the circulation 25-hydroxyvitaminD (25(OH)D) is bound to the vitamin D binding protein (DBP) and albumin. According to the free hormone hypothesis, it is, however, the free fraction that is biologically active. Polymorphisms in DBP are related to the serum level of 25(OH)D. As these polymorphisms may also affect the binding affinities for 25(OH)D, the total serum 25(OH)D may not necessary reflect the free fraction. To test this hypothesis, we will calculate the free fraction of 25(OH)D by correction for DBP and albumin content, and also measure free 25(OH)D from equilibrium dialysis and ultra filtration. Furthermore, we will relate total serum 25(OH)D as well as the free and biologically active (free- albumin-bound) 25(OH)D to the well established vitamin D effect marker serum parathyroid hormone as well as to the RNA expression in peripheral blood to evaluate the biological importance of the free versus the total fraction of 25(OH)D. We will invite 300 subjects from an ongoing vitamin D supplementation study to participate in the study which will be one visit only and include collection of blood samples.

Conditions

  • Impaired Glucose Tolerance

Sponsors & Collaborators

  • University of Tromso

    lead OTHER

Eligibility

Min Age
25 Years
Max Age
85 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2013-02-28
Primary Completion
2015-06-30
Completion
2015-08-31

Countries

  • Norway

Study Locations

More Related Trials

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 NCT01771380 on ClinicalTrials.gov