Does Treatment of Hypovitaminosis D Increase Calcium Absorption?
Condition: Osteoporosis; Osteopenia; Vitamin D Deficiency; Hypoparathyroidism; Hypercalciuria; Hypercalcemia
MeSH terms: Osteoporosis; Bone Diseases, Metabolic; Rickets; Vitamin D Deficiency; Avitaminosis; Hypercalcemia; Hypoparathyroidism; Hypercalciuria
Intervention: Vitamin D
Intervention description: 50,000 IU po qd for 15 days and 50,000 IU po twice month for 10 months (until final study visit at one year)
Intervention MeSH terms: Vitamin D; Ergocalciferols; Cholecalciferol; Vitamins
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Intervention model: Single Group Assignment
Masking: None (Open Label)
Enrollment: 19.0
Sex: Female
Minimum age: 50 Years
Maximum age: 66 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: Calcium Absorption; Intestinal Absorption of Calcium; Fractional Calcium Absorption; Stable Calcium Isotopes; Hypovitaminosis D; Vitamin D; Bone Mineral Density; Physical Function

Summary:

      The purpose is to perform a one-year study designed to assess whether treatment of
      hypovitaminosis D increases intestinal absorption of calcium, subsequent retention of calcium
      within bone, decreases bone turnover, and favorably impacts upon skeletal muscle mass,
      functional status, measures of physical function and quality of life. I hypothesize that
      treatment of hypovitaminosis D results in improved intestinal calcium absorption, greater
      retention of calcium within the bone reservoir and improved physical function, quality of
      life and muscle mass.
    

Eligibility criteria:

        Inclusion Criteria:

          -  women at least five years past onset of menopause, defined as date of last menses
             (ages reported above are the range in ages of the participants recruited to the study)

          -  serum 25(OH)D 16-24 ng/ml by reverse phase HPLC

          -  calcium intake < or = 1,100 mg daily

        Exclusion Criteria:

          -  Intake of >1,100 mg of calcium per day through the combination of diet and supplements

          -  Hypercalcemia (baseline serum calcium above the normal reference range)

          -  Nephrolithiasis, documented in the medical record or by patient report

          -  Inflammatory bowel disease, malabsorption, chronic diarrhea, or use of antibiotics
             within the past month

          -  Creatinine >2.0 mg/dL

          -  Hypercalciuria (baseline urine calcium: creatinine ratio >0.25)

          -  Current use of medications known to interfere with vitamin D and/or calcium
             metabolism, including oral steroids or anticonvulsants

          -  Ongoing or recent (past six months) use of bisphosphonates, estrogen compounds,
             calcitonin or teriparatide, as these compounds may independently affect retention of
             calcium within bone

          -  Diagnosis of, or evidence for, osteomalacia, manifest by serum 25(OH)D < 16 ng/ml or
             the presence of at least two of the following blood tests: low calcium, low
             phosphorus, or elevated alkaline phosphatase (23).

          -  Prior adult clinical fragility fracture or baseline T-score below -3.0 at the lumbar
             spine or femur