Clinical Trial: How Does Magnesium Status Influence Calcium Homeostasis?

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: How Does Magnesium Status Influence Calcium Homeostasis?

Brief Summary: The investigators aim to recruit 60 women who have agreed to participate in an existing randomized, double-blind, placebo-controlled trial (Treatment of Vitamin D Insufficiency, HSC 2009-0055). In this trial, the investigators propose to evaluate the associations between magnesium intake, magnesium stores, fractional magnesium absorption and calcium homeostasis. The investigators will stratify 60 subjects in the sub-study, ensuring that approximately 20 subjects are randomized into each treatment arm (placebo, low-dose and high-dose vitamin D). The investigators already assess calcium homeostasis throughout the study by measuring bone mineral density, fractional calcium absorption, serum and urine calcium levels, among other tests. In the sub-study of 60 women, the investigators will evaluate whether habitually higher magnesium intake increases or decreases fractional calcium absorption. The investigators will evaluate the interplay between magnesium stores, vitamin D levels and serum parathyroid hormone levels. The investigators will directly assess magnesium stores using serum magnesium and 24-hour urine magnesium levels, and will measure magnesium absorption using the dual stable isotope approach.

Detailed Summary: Use of serum magnesium isotopes to measure fractional magnesium absorption Four day food diaries to assess magnesium intake Standard urine and serum chemistries for remaining labs as noted above
Sponsor: University of Wisconsin, Madison

Current Primary Outcome: Evaluate the associations between magnesium intake, magnesium stores, fractional magnesium absorption and calcium homeostasis. [ Time Frame: 0-12 months ]

To evaluate relationships between magnesium intake and fractional magnesium absorption at baseline and 12 months, among 60 women participating in HSC Protocol 2009-0055, and to assess whether vitamin D therapy influences magnesium absorption among these women. We will also evaluate whether data collected from less than 72 hours of urine following tracer administration permits accurate assessment of fractional magnesium absorption.


Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Does vitamin D therapy have a differential impact on calcium absorption that is dependent on magnesium stores? [ Time Frame: 0-12 months ]
    To assess whether vitamin D therapy has a differential impact on calcium absorption, depending on magnesium stores. We will use data from all subjects participating in HSC Protocol 2009-0055 to evaluate whether magnesium status is a co-factor in the change in calcium absorption that occurs with vitamin D therapy.
  • Assessing relationships between magnesium status and bone mineral density. [ Time Frame: 0-12 months ]
  • Evaluate how magnesium status impacts the relationship between vitamin D levels and parathyroid hormone levels. [ Time Frame: 0-12 months ]


Original Secondary Outcome: Same as current

Information By: University of Wisconsin, Madison

Dates:
Date Received: May 4, 2012
Date Started: May 2012
Date Completion:
Last Updated: October 31, 2016
Last Verified: October 2016