Inflammation is the main determinant of low bone mineral density in pediatric inflammatory bowel disease

Aims: To assess bone mineral density (BMD) in children with Crohn's disease (CD) and ulcerative colitis (UC) and to investigate the role of inflammation and steroids on BMD. Methods: Lumbar spine areal BMD was measured by DXA, and volumetric BMD was then estimated (BMAD); inflammatory cytokines (TNF-alpha, IL-6, IL-10, and IL-12) were dosed in peripheral blood; and cumulative and daily doses of steroids were calculated. Therapy with infliximab (IFX) was considered for CD patients. Results: Fifty-six patients with IBD (35 CD, 21 UC) were studied. An inverse correlation was found between BMAD and IL-6 in patients with UC (r = -0.65); no correlation was found between BMAD and serum levels of TNF-a, IL-10, and IL-12 in all patients. Disease activity indexes use inversely correlated with BMAD (r = -0.62 in patients with CD and r = -0.64 in patients with UC). Cumulative dose of corticosteroids and duration of therapy did not correlate with BMAD. The 10 patients with CD who were treated with IFX had higher BMAD (-1 +/- 0.8) than those never treated with IFX (-1.8 +/- 0.8). Mean Pediatric Crohn's Disease Activity Index and body mass index in patients with CD (R-2 = 0.48) and IL-6 level in patients with UC (R-2 = 0.43) were found to be independent and significant predictors of BMAD. Conclusions: In children with IBD, inflammation is an important determinant of bone loss, as shown by the correlation of BMAD with serum IL-6 and with disease activity indexes as well as by the beneficial effect of IFX on bone density. Corticosteroids seem to be a less important variable in pediatric IBD-related BMD reduction than previously believed.