Bone mineralization in children with inflammatory bowel disease: What is the role of zinc?

Background/aims: Bone demineralization is a significant problem in pediatric inflammatory bowel disease. Contributing factors include inadequate nutrition, corticosteroid therapy and decreased physical activity. Although zinc is needed for osteoblastic activity and collagen synthesis, its role in bone development is uncertain. The aim of this study was to investigate the relation between the serum zinc level and bone mineral indexes of 28 children with inflammatory bowel disease. Methods: Bone mineral content and bone mineral density at lumbar 1-4 vertebrae were measured by dual energy X-ray absorptiometry in all patients and 56 controls. Serum zinc levels of patients and 31 controls were determined by spectrophotometric method. Results: The mean bone mineral density values of patients and controls were 0.661+/-0.201 g/cm(2) and 0.751+/-0.175 g/cm(2), the mean bone mineral content values were 33.357+/-17.104 g and 38.968+/-14.663 g, and the mean serum zinc levels were 101.2+/-28.8 mu g/dl and 108.9+/-15.9 mu g/dl, respectively. All controls had normal serum zinc level; however, 11 (39.3%) patients had low serum zinc level (p=0.000). The ratio of patients with Z-score below the -2SD was higher in patients with low zinc level than in patients with normal zinc level (70% vs. 42.8%). Conclusions: Although insignificant, some of the children with IBD had low levels of serum zinc and these patients had lower Z-scores than the others. Further studies including large numbers of patients may reveal a certain effect of zinc on bone development in patients with inflammatory bowel disease.