ESPE Yearbook of Paediatric Endocrinology

christine.martinez-vinson@aphp.fr J Pediatr Gastroenterol Nutr. 2021; 73: 231-235. PMID: 33908740.

Brief Summary: This retrospective study evaluated longitudinal changes in bone mineral density (BMD) in children and adolescents with Crohn disease (CD), and the risk factors for low BMD. Low BMD (defined as BMD Z score ≤ -2.0) was present in 18.7% of patients at diagnosis and in 16% at the end of follow up.

193 children with CD, aged 2 to 18 years, underwent dual-energy X-ray absorptiometry (DXA) both at diagnosis and at the end of follow-up between 1999 and 2018. Data were checked using two different sources (a medico-administrative database and a national register).

Lumbar spine (LS) BMD values were lower than total body less head (TBLH) values, both at diagnosis and at the end of follow-up. Multivariate analysis showed that height growth impairment or low body mass index (BMI) were associated with low BMD at diagnosis, while at the end of follow-up only cumulative steroid dose was associated with low BMD.

The large sample size and the double source of data are strengths, but its retrospective design and the lack of some relevant data, such as pubertal status, physical activity, diet, and calcium/vitamin D intakes limits its significance. Another limitation is related to the use of DXA. Although DXA is still considered the most appropriate method for BMD assessment, this technique analyzes bone mineral content by area and not by volume, not considering the three-dimensional structure of the bone. Thus, DXA intrinsically underestimates BMD of children with linear growth delay.

Low BMD is the most common extra-intestinal manifestation (from 6 to 44%) after inflammatory bowel disease (IBD) diagnosis. This study confirms that long-term glucocorticoid therapy is the main risk factor associated with low BMD. Special attention must be given to patients with height growth delay and/or low BMI at diagnosis. As the authors suggest, an age-appropriate counseling for nutrition and physical activity, may empower young patients and their families to prevent calcium/vitamin D deficiency and decreased skeletal muscle mass, which can contribute to poor bone health in IBD.