Endocrine Abstracts

Objective: Deficits in skeletal muscle and function is a recognised feature of Osteogenesis Imperfecta (OI). Less is known about longitudinal change in body composition in OI. Our objective was to perform a retrospective analysis of longitudinal change in body with focus on lean mass and fat mass in children with OI.

Methods: Data was collected from 29 children, with a diagnosis of OI, who had at least two DXA scans performed between 2015 and 2022. Assessed variables of height, body mass index (BMI), lean mass index (LMI) and fat mass index (FMI), converted to standard deviation scores (SDS), were compared. Results were reported as median (range).

Results: Median age at baseline and follow-up were 10.7 and 14.2 years, respectively. Median height-SDS at baseline was -1.10 (-3.64, 1.62), which was significantly lower than the normal population (P < 0.001). Median height-SDS at latest follow-up was -0.80 (-3.31, 1.57), which was not significantly different from baseline (P = 0.870). Median BMI-SDS at baseline was 0.15 (-2.31, 2.95), which was not significantly different than the normal population (P = 0.804). Median BMI-SDS at latest follow-up was 0.02 (-2.50, 3.76), which was not significantly different from baseline (P = 0.730). Despite normal BMI, abnormalities in body composition were noted. At baseline, median LMI-SDS was -2.43 (-4.05, 0.66), which was significantly lower than the normal population (P < 0.001). Median LMI-SDS at follow-up was -1.78 (-4.49, 1.61), which was not significantly different from baseline (P = 0.080). At baseline, median FMI-SDS was 0.57 (-0.62, 2.97), which was significantly higher than the normal population (P = 0.001). Median FMI-SDS at follow-up was 0.62 (-0.59, 5.876), which was not significantly different from baseline (P = 0.540).

Conclusion: Children with OI have abnormal body composition throughout childhood typically with low lean mass and relatively high fat mass. These abnormalities in body composition do not change with follow-up. Strategies to improve lean mass, including physical or medical therapies, should be explored in OI given the close relationship between muscle and bone.