Adolescent patients with Crohn disease have increased bone marrow adiposity, especially early in the disease course, according to study results published in Bone.
The findings are based on a pilot study of 5 patients (mean age, 13.4 years [range, 13-14]; 4 boys) from a single inflammatory bowel disease center. All patients were prospectively enrolled from 2011 to 2013.
The researchers obtained clinically relevant information from a retrospective chart review, which included dual-energy X-ray absorptiometry (DXA) measures to assess bone mineral density and body composition, biochemistries, and the clinical course of Crohn disease. The study participants were treated initially with systemic glucocorticoids and then received immunosuppressive therapy.
The patients had a mean fat fraction of 67.8% (range, 44% to 84%). Healthy adolescents have persistent hematopoietic marrow with approximately 40% to 50% fat in the long bone metaphyses, the researchers noted. Magnetic resonance spectroscopy (MRS) showed that the largest fat fractions occurred in participants with the shortest disease duration, and the smallest fat fractions were found in participants with the longest disease duration.
T1 values ranged from 723 msec to 1088 msec, with the highest T1 relaxation time corresponding with the lowest marrow fat fraction (44%) assessed with MRS.
DXA Z-scores were low or borderline low in 3 patients. The 3 participants who had their body composition assessed with appendicular lean mass index appeared to have low lean mass, with Z-scores ranging from -1.5 to 0.5, which was inversely associated with disease duration.
Study limitations included the small number of participants, cross-sectional design, and absence of matched control individuals. In addition, the timing was not uniform between glucocorticoid exposure and imaging assessment, and the researchers were unable to obtain biochemical bone evaluations including bone turnover markers.
“The current data suggest that adolescent patients with Crohn disease have increased marrow adiposity, compared [with] healthy adolescents,” the study authors wrote. “These findings suggest that [magnetic resonance imaging] (MRI) may be a sensitive marker of Crohn disease activity on bone, especially early in the disease course, while DXA may be better at assessing chronic effects on bone over time. Further assessment of novel bone marrow imaging with MRI is needed to understand the role of adipocytes and potential adverse effects on osteogenesis, and the relationship between altered body composition and bone marrow adiposity.”
Disclosure: One of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Gordon RJ, Pappa HM, Vajapeyam S, et al. Bone marrow adiposity in pediatric Crohn’s disease. Bone. Published online June 3, 2022. doi:10.1016/j.bone.2022.116453