Background: The effect of adiposity on bone mass in the early phases of inflammatory bowel disease (IBD) in children and adolescents is unclear.

Aims: To determine the role of adiposity on bone mass in the first 3 years of diagnosis of IBD.

Hypothesis: Increased adiposity will be associated with increased bone mass in both the controls and IBD subjects.

Setting: University tertiary institution.

Methods: Height-adjusted bone mineral density (BMD) z-scores of 25 subjects, age 13.97 ± 2.70y, diagnosed with IBD for < 4 years were compared to 24 controls, age 13.65 ± 2.60y. Overweight was defined as BMI of ≥85^th but <95^th percentile, and obesity as BMI ≥95^thpercentile. Severity of IBD was determined by the Pediatric Crohn’s Disease Activity Index and Lichtiger Colitis Activity Index.

Results: Prior to stratification by BMI criterion, height-adjusted BMD z-scores were non-significantly lower in IBD subjects vs. controls for both the femoral neck (-0.8 ± 1.1 vs. -0.06 ± 1.1, p=0.070) and lumbar vertebrae (-0.4 ± 1.2 vs. 0.2 ± 1.2, p=0.086). Following stratification, height-adjusted BMD z-scores were significantly lower in the overweight/obese IBD subjects vs. overweight/obese controls for femoral neck (-0.9 ± 0.9 vs. 0.3 ± 1.3, p=0.032); and non-significantly lower for the lumbar spine z-score (-0.4 ± 1.6 vs. 0.5 ± 1.3, p=0.197). BMD z-score had no relationship with the duration of disease, steroid therapy, and the severity of disease.

Conclusion: Adiposity was associated with reduced bone mass in the early phases of IBD, but with increased bone mass in the controls.