Association between MASLD and bone mineral density in Chinese aged 20-50: a cross-sectional study

Purpose Hepatic osteodystrophy (HOD) is a metabolic bone disorder characterized by bone loss in patients with chronic liver diseases (CLDs). Metabolic dysfunction-associated steatotic liver disease (MASLD) is among the most common CLDs, and its burden is increasing in younger populations; however, its association with bone mineral density (BMD) in young adults remains uncertain. We evaluated the association between biopsy-defined MASLD and BMD in Chinese adults aged 20–50 years. Methods This cross-sectional study included 314 participants from Jiangsu Province Hospital, comprising 157 patients with MASLD and 157 participants without MASLD after 1:1 propensity score matching for age and sex. BMD at the lumbar spine (LS) and femoral neck (FN) was measured by dual-energy X-ray absorptiometry. Liver biopsy was used to assess hepatic steatosis severity, MASLD activity score (NAS), and histological progression in participants with obesity. Multiple linear regression models were used to evaluate the association between MASLD and BMD. Results After adjustment for confounding factors, MASLD was associated with lower LS BMD [β = -0.069 (95% CI: -0.123, -0.016)] and FN BMD [β = -0.054 (95% CI: -0.102, -0.006)]. In sex-stratified analyses, the inverse association with LS BMD was observed in females but not in males. In age-stratified analyses, the inverse association with LS BMD was more evident among participants aged >31 years. LS BMD and FN BMD decreased significantly with increasing hepatic steatosis severity. Progression from non-MASLD to MASLD without MASH and MASH was associated with a significant decreasing trend in LS BMD, whereas the trend for FN BMD did not reach statistical significance. In NAS-based supplementary analyses, the trend for LS BMD was borderline after full adjustment, and the trend for FN BMD was not significant. Ballooning was inversely associated with LS BMD [β = -0.063 (95% CI: -0.111, -0.015)], whereas lobular inflammation and fibrosis were not. Conclusion Biopsy-defined MASLD was associated with lower LS BMD and FN BMD in Chinese adults aged 20–50 years after adjustment for confounding factors. These findings provide clinical evidence for further mechanistic studies of MASLD-related bone loss and the liver-bone axis.