Monthly Boluses Versus Daily Doses for Correcting Blood Vitamin D Deficit in Obese Children and Adolescents

Childhood obesity prevalence is increasing and is a serious public health challenge. Indeed, according to INPES in 2006, overweight and obesity were affecting 18 % of French children between 3 and 17 years. 3 % of the boys and 4 % of the girls were classified as obese. Obese children are likely to develop chronic disease, starting at paediatric age, as cardiovascular or bone diseases, or type 2 diabetes.

Vitamin D deficiency is recognized to play an essential role in bone metabolism and arterial hypertension and type 2 diabetes development.

Obesity, in adults like in children, is associated with vitamin D deficiency. Common explanations for this low serum concentration of 25(OH)D in obese are the sequestration and/or the volumetric dilution of this lipid-soluble vitamin by adipose tissue. Therefore, obese population is at higher risk of developing cardiovascular and metabolic complications.

The nutrition comity of French Pediatric Society (SFP) edit vitamin D supplementation recommendations (2012) for adolescents at risk of deficit: supplementation by trimestral loading dose of 80 000 to 100 000 UI of vitamin D. However, for obese patients, the deficit is difficult to cure with classical loading doses. It seems that these patients need higher dose of Vitamin D (two to three times higher). Likewise, the optimum scheme of administration (daily vs monthly) was never evaluated.

Given new physiopathological data on pleiotropic role of vitamin D (on bone, cardiovascular system, adipose tissue) and in light of consequence of obesity on these systems, it seems essential to obtain data on vitamin deficit correction in obese children and adolescents.

In this context, the OBEVIDOS study, randomised multi-centre prospective in 156 obese children and adolescent will allow us for :

* evaluate vitamin D correction effect by two scheme of administration
* establish an inventory of vitamin D status in this population
* Modeling and simulation of vitamin D concentration in obese children and adolescents using a mathematical PBPK model
* study, in a patient sub-group, the impact of vitamin D deficit and of obesity by itself on bone, by analysing bone micro-architecture


Eligibility Criteria:
Inclusion Criteria:

* Aged between 5 to 18 year-old
* Being obese (BMI \>97th percentile for age and gender using the WHO references)
* Patients (parents) having given their informed consent
* Patient having insurance from the national health system

Exclusion Criteria:

Children will be excluded from the study if:

* Vitamin D supplementation in the 3 months preceding the inclusion visit (V1)
* They suffer from symptomatic vitamin D deficiency (tetany, muscular hypotonia, hypocalcaemic seizure) or present signs of rickets at the X-ray (osteopenia and cortical thinning of the long bones, stress fractures, and metaphyseal widening and fraying. The earliest rachitic change is a loss of demarcation between the metaphysic and growth plate and loss of the provisional zone of calcification). A 10-point radiographic scoring system will be used to assess the presence and the severity of rickets on the basis of knee and wrist findings.
* They suffer from a chronic disease such as granulomatous conditions, Williams syndrome, or hypothyroidism predisposing to hypocalcaemia or in case of hypercalcaemia, liver/kidney disease, malabsorption diseases.
* They are under treatment of anticonvulsivants/barbiturates or steroids which increase the catabolism of 25(OH)D.
* Contraindications to the class of drugs under study, e.g. known hypersensitivity or allergy to class of drugs or the investigational product.
* Pregnancy.
* Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant.
* Previous enrolment into the current study