Vitamin D, Bones, Nutritional and Cardiovascular Status
Condition: Vitamin D
Study type: Interventional

Summary: 
      Vitamin D is not seen anymore only as a phosphocalcic hormone, but also as having an effect
      on global health (anti-infective, anti-inflammatory, anti-tumour roles and cardiovascular
      protection).

      The link between vitamin D deficiency and osteomalacia lesions is well-known. In paediatrics,
      systematic vitamin D supplementation of infants and toddlers, associated with milk
      enrichment, has allowed an almost total disappearance of rickets. Vitamin D repletion was
      defined as the minimal concentration that enables the prevention of rickets in children and
      osteomalacia in adults, that is approximately 8 ng/mL (20 nmol/L). However, in 2010, most of
      the international experts agreed to set minimal threshold of 25 OH vitamin D serum
      concentration, higher than the one previously admitted, with a limit of 20 ng/mL (50 nmol/L)
      to define a vitamin D deficiency and a limit of 30 ng/mL (75 nmol/L) to define vitamin D
      insufficiency in adults. In the paediatric population, the consensus is less obvious and we
      consider that a serum concentration of minimum 20 ng/mL is necessary.

      A study on more than 200 children from Lyon, followed in the paediatric nephrology unit and
      having a renal function normal or sub-normal, demonstrated an important prevalence of vitamin
      D deficiency (75%) in adolescents and pre-adolescents.

      Concurrently, the appearance of new bone imaging techniques (especially high-resolution
      peripheral quantitative computed tomography HR-pQCT) improved bone status evaluation in a
      non-invasive manner.

      Given the new pathophysiological data on pleiotropic role of vitamin D (bone, cardiovascular
      system, adipose tissue) and given the proportion of French children possibly suffering from
      vitamin D deficiency, it seems urgent to actualize current recommendations regarding
      systematic supplementation in vitamin D. This transversal study on 200 healthy children and
      adolescents will allow to have an overview of vitamin D status in French healthy children and
      adolescents, studying with non-invasive, safe, reliable and innovative tools, the theoretical
      targets of vitamin D (bones, cardiovascular system and nutritional status); and then to lay
      the foundations of therapeutic trials aiming to evaluate the mode of vitamin D
      supplementation for healthy children and adolescents; while having a cohort for HR-pQCT
      measurements, that will allow us to have French reference range in a 10-17 year-old
      population, for this innovative, non-invasive and low radiation exposure technique.
    

Detailed description: 
      To study the correlation between bone assessment by high-resolution peripheral quantitative
      computed tomography (HR-pQCT) and vitamin D serum concentration.
    

Intervention name(s): Exploration of Vitamin D roles
Intervention type(s): Other
Intervention description(s): Visit 1: questioning, physical examination, blood sampling (including plasma collection for future genetic analyses), carotid ultrasound
Visit 2 (same day as visit 1 or maxi 3 months later): HR-pQCT, dual energy x-ray absorptiometry (DXA), iontophoresis of acetylcholine and sodium nitroprusside
Intervention MeSH terms: Vitamin D
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Health Services Research
Keywords: Vitamin D; bone; cardiovascular status; nutritional status