Study to Observe the Capability to Absorb Calcium as an Measure of Adequate Levels of Vitamin D
Condition: Postmenopausal; Vitamin D Deficiency
MeSH terms: Vitamin D Deficiency
Study type: Interventional

Summary: 
      The purpose of this study is to determine the capability to absorb calcium as a measure of
      the sufficient levels of Vitamin D. Calcium absorption will be measured at baseline and after
      vitamin D3, by dual calcium isotope technique using stable isotopes in post menopausal women
      between the ages 50 and 70yrs. Subjects will have a screening visit, first and final visits.
      Subjects will be randomly assigned to a placebo or daily doses of vitamin D3. The specific
      aim of this study is to determine the level of vitamin D that will maximize the absorption of
      calcium and establish the relationship between the administered calcium dose and the actual
      absorbed calcium dose versus administered dose of Vitamin D and the serum levels of Vitamin
      D.
    

Detailed description: 
      The specific aims of this project are:

        1. To determine the level of 25OHD that maximizes calcium absorption efficiency.

        2. To describe the dose response curve of calcium absorption to vitamin D intake and serum
           25OHD.

      This will be a randomized, double-blind, placebo-controlled trial of healthy postmenopausal
      females to determine the individual and combined effects of calcium and vitamin D
      supplementation.70 female participants, ages 50 to 70 years of age who are menopausal for
      over 1 year will be recruited into the study . The patients participation in this study will
      last about 10 weeks. Approximately 70 subjects from Winthrop University Hospital and the
      surrounding area will participate in this study. There is a total of 3 visits. Patients will
      be fasting for all visits. The first visit is a screening visit to determine if the patients
      qualify.

      At visit 2, the patients will be given a light breakfast and asked to drink an 8 ounce glass
      of milk or calcium fortified orange juice containing a calcium isotope. After breakfast, the
      doctor or nurse will start an intravenous infusion and inject the patient with an IV solution
      containing a calcium isotope. This is a stable calcium isotope that is not radioactive and
      has no known toxicity. The patients will also be asked to collect a 24 hour urine and return
      it to us the next day.

      The volunteers will be divided into four groups:

      The first group will take 800 iu daily of vitamin D supplementation. The second group will
      take 2000 iu daily of vitamin D.The third group will take 4000 iu vitamin D and the fourth
      group will only take placebos. Visit 3 is essentially the same as visit 2, with subjects
      returning unused study medication and given new tablets

      Food frequency questionnaires will be filled out at the initial visit and final visit. Diet
      will be assessed using 3-day diet history form and NutritionPro analysis software. Patients
      will be asked to refrain from taking other vitamin D supplements and to continue their usual
      calcium intake.
    

Intervention name(s): Dual isotope technique
Intervention type(s): Other
Intervention description(s): Dual isotope technique using stable isotopes
Other intervention name(s): Kinetic study; dual stable isotope
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Diagnostic
Keywords: Post menopausal; Vitamin D sufficiency; Calcium absorption efficiency; Dual isotope technique