Association between total bilirubin and bone mineral density level in adolescents

Background Increasing bone mass accumulation in adolescence and obtaining greater peak bone mass is one of the effective methods to prevent osteoporosis in the future. We aimed to examine the association between total bilirubin and bone mineral density (BMD) level in adolescents. Methods We used the data from 2005-2010 and 2013-2014 cycles of National Health and Nutrition Examination Survey (NHANES). The BMD levels in the region of lumbar spine and femoral regions, including total femur, femoral neck, trochanter, and intertrochanter were measured. Univariable and multivariable linear regression model were used to assess the relationship between total bilirubin concentration and BMD. Results A total of 3741 participants aged 12-19 years were ultimately included in the study. There were 1997 (53.38%) males and 1744 (46.62%) females. Univariate analysis results showed that age, sex, race, education, income, body mass index, dietary calcium intake, and diabetes were correlated with BMD levels. Compared with the lowest quartile of total bilirubin concentration, the highest quartile of total bilirubin concentration was positively associated with BMD levels in the regions of total femur (beta = 0.036, 95% CI = 0.021 to 0.050, P < 0.001), femur neck (beta = 0.030, 95% CI = 0.016 to 0.044, P < 0.001), trochanter (beta = 0.033, 95% CI = 0.019 to 0.046, P < 0.001), intertrochanter (beta = 0.040, 95% CI = 0.023 to 0.056, P < 0.001), and lumbar spine (beta = 0.032, 95% CI = 0.018 to 0.045, P < 0.001). We also observe the same trend in sensitivity analysis (P for trend < 0.001). Conclusion Our study demonstrated that total bilirubin concentration was positively associated with BMD levels in adolescents in United States. Total bilirubin concentration might be a protective marker against bone loss in adolescents.