Bone microarchitecture evaluated by HR-pQCT in Chinese adolescent and pediatric patients with X-linked hypophosphatemia

Abstract Context X-linked hypophosphatemia (XLH) is the most common form of heritable hypophosphatemic rickets. Previous studies have found deteriorated bone microarchitecture in adults with XLH. Detailed studies on the skeletal microarchitecture of adolescent and pediatric patients with XLH are still lacking. Objective This study aimed to evaluate bone geometry, density, microarchitecture, stiffness in adolescent and pediatric patients with XLH by using high-resolution peripheral quantitative computed tomography (HR-pQCT). Method This study utilized HR-pQCT to assess bone geometry, density, microarchitecture, and stiffness in 106 Chinese adolescent and pediatric patients with XLH. Result Compared with sex- and age-matched controls, patients with XLH had significantly higher trabecular area (Tb.Ar), lower total volumetric bone mineral density, lower cortical volumetric BMD (Ct.vBMD), and lower stiffness at both the distal radius and the tibia after adjusting for height and weight. Alkaline phosphatase Z score (ALP-Z), a marker to reflect the disease activity of rickets, was negatively correlated with Ct.vBMD and cortical thickness at the distal radius, and Ct.vBMD at the distal tibia, and positively correlated with cortical porosity at the distal tibia. We developed an online calculator to estimate Tb.Ar, Ct.vBMD, and stiffness of the distal tibia of adolescent and pediatric patients with XLH based on clinical general characteristic and biochemical indicators. Conclusion The bone microarchitecture of adolescent and pediatric patients with XLH had deteriorated, and ALP-Z was negatively correlated with the skeletal quality of adolescent and pediatric patients with XLH, especially in the cortical bone. HR-pQCT parameters can be estimated using clinical characteristics and biochemical indicators, which may assist physicians to monitor the disease progression in areas without HR-pQCT access.