ESPE Abstracts

Introduction: X-linked hypophosphatemic rickets (XLH) is characterized by a mineralization disorder in the growth plate and cortical and trabecular bones, resulting in bone deformities with anthropometric changes and potential alterations in body composition.

Objective: To evaluate the body composition of 12 children and adolescents with XLH compared to healthy controls by anthropometric and densitometry data.

Methods: The cross-sectional analysis used anthropometric and densitometric data from the confirmed XLH patients in regular conventional treatment and their respective sex, age, and pubertal stage-matched controls. In these groups, body composition parameters analyzed by dual-energy X-ray absorptiometry (DXA) included bone mineral content (BMC) and total body less head bone mineral density (subtotal BMD), lean mass (LM), fat mass (FM), and percentage of body fat (%). Also, the fat mass and lean mass indexes (FMI and LMI, respectively) were calculated as the FM (kg) and LTM (kg) divided by the height in meters squared and compared between groups. Also, the subtotal-BMD Z score adjusted for the height Z score (subtotal-BMD–HAZ) was calculated.

Results: 66.8% (8) of the sample were female, 66.8% (8) were pubertal, and the median age was 11 [6;18] years. Despite the shorter stature of XLH patients compared to controls (P<0.01), there was no significant difference between the groups in body mass index (P=0.29). XLH patients had lower BMC compared to controls (P<0.05), but subtotal-BMD–HAZ tended to be more significant in the XLH group (P=0.10). Meanwhile, fat mass and lean mass were significantly lower in XLH patients (P<0.05 and P<0.01, respectively), but the percentage of body fat was equivalent between the groups (P=0.64). Also, there was no significant difference between the groups regarding FMI and LMI (P=0.96 and P=0.60, respectively).

Conclusion: Although individuals with XLH had lower fat mass (FM) and lean mass (LM) compared to controls, it is crucial to consider the influence of their shorter stature on these measurements, and adjusting the body composition evaluation for height would yield more accurate data. While XLH is associated with impaired skeletal development, the potential redistribution of body composition in XLH should be examined in the context of hormonal factors and treatment effects on muscle and fat accrual.