Low Bone Mineral Density in Children and Adolescents with Inflammatory Bowel Disease: a Population-based Study from Western Sweden

Background: Low bone mineral density (BMD) has been recognized as a potential problem in children with inflammatory bowel disease (IBD). The aim of the study was to investigate BMD in Swedish children and adolescents with IBD and to evaluate possible factors affecting BMD.

Methods: To evaluate BMD, all patients (n = 144) underwent a dual-energy X-ray absorptiometry (DXA) of the whole body and the spine. BMD values were expressed as Z-scores using normative pediatric data from Lunar (GE Medical Systems).

Results: In this population-based study, the lowest BMD values were found in the lumbar spine. The entire IBD group showed significantly lower BMD Z-scores of the lumbar spine (L2-L4) in comparison to healthy references (-0.8 standard deviation [SD], range -5.9 to 3.7 SD, P < 0.001). Decreased BMD with a Z-score < -1 SD occurred in 46.7% of the individuals with Crohn's disease (CD) and in 47.0% of those with ulcerative colitis (UC). Low BMD with a Z-score ≤ -2 SD was present in 26.7% of the patients with CD and in 24.1% of the UC patients. In a multiple regression model with BMD lumbar spine as the depending variable, possible factors associated with lower BMD were male gender, low body mass index (BMI), and treatment with azathioprine.

Conclusions: Low BMD is prevalent in Swedish pediatric patients with IBD. Possible risk factors for lower BMD are male gender, low BMI, and treatment with azathioprine, as a probable marker of disease course severity.