Risk Factors of Low Bone Mineral Density in Newly Diagnosed Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract with an increasing worldwide incidence. IBD is frequently diagnosed during childhood in the adolescent period of ongoing growth and development, and it can affect patients' linear growth, puberty, nutrition, and bone health. Therefore, its treatment and monitoring are critical to prevent secondary outcomes. However, few studies have highlighted the association between pediatric IBD and skeletal outcomes in Asian populations. We aimed to identify the prevalence and risk factors for low bone mineral density (BMD) in Korean children and adolescents with newly diagnosed IBD. Patients aged 10-18 years diagnosed with either Crohn's disease (CD) or ulcerative colitis (UC) who underwent lumbar spine bone mineral density (LSBMD) and femoral bone mineral density (FBMD) analyses via dual-energy X-ray absorptiometry at the time of IBD diagnosis were included. Low BMD was considered when the age- and sex-matched BMD Z-score was <-1.0. The LSBMD and FBMD Z-scores were correlated with clinical parameters, including general characteristics, anthropometry, and IBD-associated laboratory markers. Regression analyses were performed to identify the risk factors for low BMD. Although the general characteristics between CD (n = 42) and UC (n = 9) groups did not differ, the mean Z-scores of LSBMD and FBMD of the 51 subjects were -0.11 ± 1.24 and -0.58 ± 1.38, respectively. Furthermore, 7.8% and 18% of the study subjects had LSBMD and FBMD Z-scores < -2.0, whereas more than 50% had scores of 0--1.0. Among the clinical factors, body mass index (BMI) Z-score, duration of clinical manifestations, and serum alanine aminotransferase and selenium levels were associated with LSBMD Z-scores in the final multivariate regression analyses. Odds ratios of BMI < -2.0 standard deviation for low LSBMD and FBMD Z-scores were 31.97 and 41.45, respectively. A BMI Z-score < -0.93 was determined as the best cut-off for predicting low BMD. In newly diagnosed pediatric IBD, a substantial number of children are likely to have low BMD in prior to initial treatment while lower BMI, longer duration of clinical manifestation, and higher selenium concentration could affect initial BMD status. Routine bone health surveillance from initial IBD diagnosis throughout the treatment's completion is recommended for preventing the early development of secondary osteoporosis.