How Does Magnesium Status Influence Calcium Homeostasis?

University of Wisconsin (UW)

Status and phase: Completed; Phase 4

Conditions: Calcium Metabolism Disorders; Magnesium Deficiency

Treatments: Dietary Supplement: vitamin D3

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT01593501

R01AG028739-01A2 (U.S. NIH Grant/Contract)

HSC #2011-0547

Details and patient eligibility

About

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.

Full description

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

Enrollment: 39 patients

Sex: Female

Ages: 30 to 75 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• participants eligible for the study "Treatment of vitamin D insufficiency" are eligible for participation in the current sub-study

Exclusion criteria

• identical to those covered in HSC #2009-0055

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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39 participants in 3 patient groups, including a placebo group

High dose vitamin D

Active Comparator group

Description:

50,000 IU vitamin D3 every 15 days, with a loading dose of 50,000 IU per day for the first 15 days of an approximate 365-day treatment.

Treatment:

Dietary Supplement: vitamin D3

Low dose vitamin D

Active Comparator group

Description:

800 IU vitamin D3 every day of an approximate 365-day treatment.

Treatment:

Dietary Supplement: vitamin D3

Placebo

Placebo Comparator group

Description:

A pill that looks like the low/high dose vitamin D pills, but contains no vitamin D. Given to preserve the double-blind nature of the study.

Treatment:

Dietary Supplement: vitamin D3