Vitamin D Levels in Children With IBD

Vitamin D is essential for bone mineralization. The prevalence of vitamin D insufficiency [serum 25-hydroxy-vitamin D concentration (25OHD) ≤ 20 ng/mL] is high among adults with inflammatory bowel disease (IBD), and even higher in pediatric patients with IBD. Protein-losing enteropathy could represent both an etiologic factor for hypovitaminosis D, and an obstacle in treating it in IBD patients. There are currently no guidelines for the treatment of hypovitaminosis D in adults or children with IBD. Moreover we have obtained evidence that optimal vitamin D stores (25OHD ≥32 ng/mL) may not be maintained throughout the year in patients with IBD following current RDA recommendations. On the other hand, the prevalence of low bone mineral density is high among young patients with IBD, during a period in their lives when they should experience the most rapid acquisition of bone mass. Optimization of vitamin D status and its impact on the bone health of children with IBD has not been studied. In addition, vitamin D may play an important role in the regulation of the immune system as supported by animal models of colitis and in vitro human studies.

Prospective studies of the effect of vitamin D supplementation on disease outcomes have not been undertaken in children with IBD to date. We aim to perform a) a randomized controlled trial to compare the efficacy of 3 regimens in treating vitamin D insufficiency in pediatric patients with IBD over a period of 6 weeks. We will also evaluate the effects of each regimen on markers of bone resorption, bone formation and parathyroid hormone levels, and the relationship between the magnitude of gastrointestinal protein loss, as reflected by clearance of fecal alpha -1-antitrypsin, and the efficacy of the treatment. b) We also aim to perform a randomized controlled trial to compare the efficacy of 2 regimens of different doses of oral vitamin D2 in maintaining optimal vitamin D stores in pediatric patients with IBD over a period of 2 years. We intend to study the effect of each regimen on a) bone mass acquisition (measured via DXA and pQCT) and bone strength (measured via pQCT), b) bone formation and resorption markers and parathyroid hormone, and c) disease outcomes and disease severity over the same period of time.