Young inflammatory bowel disease patients have low bone mass

By Laura Cowen

Children and adolescents with inflammatory bowel disease (IBD) have significantly lower bone mineral density (BMD) than their healthy peers, even after adjusting for pubertal delay, Finnish researchers report.

The decreased BMD was accompanied by an increase in vertebral abnormalities suggestive of subclinical vertebral fractures (VFs).

"These observations warrant careful follow-up and emphasize the need for more active preventive measures, including adequate vitamin D supplementation, in children and adolescents with IBD," remark Saila Laakso (University of Helsinki) and co-authors of the study.

The researchers conducted the cross-sectional cohort study among 80 IBD patients (54% women) aged 5‑20 years with a median disease duration of 3.4 years, and 80 age- and gender-matched healthy controls.

Of the patients with IBD, 51 had ulcerative colitis, 26 had Crohn's disease, and three had unspecified colitis.

After adjusting for bone-age (a surrogate for pubertal delay), Laakso and team found that IBD patients had significantly lower BMD for the lumbar spine and whole body than controls. They also had significantly lower height-adjusted whole-body bone mineral content (BMC) than controls.

This shows that "the low BMD values are not solely due to short stature or delayed skeletal maturation," write the authors in Calcified Tissue International.

Indeed, logistic regression analysis showed that, among the patients with IBD, a cumulative weight-adjusted prednisolone dose above 150 mg/kg for the preceding 3 years was associated with a significant 5.5-fold increased the risk for low whole-body BMD.

Laakso and team also found that lean mass and fat mass did not differ between the groups, but IBD patients had significantly lower whole-body BMC relative to muscle mass than controls.

The two groups had a similar fracture history, with 11% of IBD patients and 20% of controls reporting a previous peripheral fracture. However, analysis of VF assessment images from dual-energy X-ray absorptiometry showed that abnormal vertebral morphology was significantly more common in IBD patients than in controls, at 11% versus 3%.

The researchers conclude that "longitudinal studies with sufficient follow-up time beyond adolescence are needed to clarify the risk and significance of reduced peak bone mass in pediatric IBD patients."

In addition: "Screening of subclinical VFs with X-ray images is needed to estimate the real risk of VFs in pediatric IBD patients."

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