The triangular relationship of serum uric acid, osteoporosis or osteopenia, and body mass index for men and postmenopausal women

Background Osteoporosis (OP) is a systemic bone disease characterized by reduced bone density and quality, leading to increased bone fragility and a higher risk of fractures. The relationship between serum uric acid (SUA) levels and OP or osteopenia remains controversial, as does the impact of weight change on these conditions. Moreover, few studies have investigated whether body mass index (BMI) serves as a mediator in the association between SUA and OP or osteopenia. Objective This study aimed to elucidate the complex interactions between SUA, OP or osteopenia, and BMI. Methods A cross-sectional study from the REACTION study was conducted to examine the association between SUA and OP or osteopenia. Various logistic regression and restricted cubic spline models were employed to analyze the pairwise correlations among these variables, and interaction analysis was performed to assess differences between subgroups. Mediation models were utilized to determine the mediating role of BMI. Results The findings indicated that both SUA and BMI were inversely associated with OP or osteopenia, while a positive correlation was observed between SUA and BMI. Analysis of the dose-response relationship between SUA and OP or osteopenia showed a linear negative correlation, and a significant nonlinear association between BMI and the risk of OP or osteopenia. No significant interactions were found within subgroups. Additionally, BMI was found to mediate 13.6% of the potential effects of SUA on OP or osteopenia. Conclusions SUA appears to have a protective effect against OP or osteopenia, with BMI potentially serving as a mediator. Thereby, maintaining SUA and BMI within an optimal range may.